Chapter One

Chapter OneThe big picture

– the Periodic Table

Handouts and Worksheets‘The Chemical Investigator’ pages 5 – 11Study On – worksheets 1 & 2

Matter

• Every material thin that you can see, smell and touch, that occupies space and has mass, is a form of matter.

• Matter is made up of very small particles and may exist in solid, liquid or gaseous states.

• The behaviour of these particles is explained by the particle model, or kinetic theory of matter.

The Kinetic Theory of MatterKey Points

• Matter is made up of tiny, invisible moving particles• Particles of different substances have different sizes• Lighter particles move faster than heavier ones at a particular

temperature• As temperature rises, the particles move faster• In a solid, the particles are very close and vibrate in fixed

positions• Ina liquid, the particles are a little further apart. They have

more energy and they can move around each other• In a gas, the particles are far apart. They move rapidly and

randomly in all the space that surrounds them.

Properties of Solids, Liquids and gases

• Solids have definite shapes and volumes– Crystalline solids (salt, diamonds) have particles

arranged in regular, repetitive patterns– Particles are able to vibrate but not move– Amorphous solids do not have this regular

structure (eg rubber, putty)

Properties of Solids, Liquids and gases

• Liquids have a definite volume, taking the shape of the container but their surfaces are always horizontal– Liquid particles move further apart than those in a

solid and are in constant motion, free to move– Liquids can flow

• Gases take the same shape and volume as their container, free to move in any direction.

Matter is usually defined as anything that has mass and occupies space.

Gas Liquid Solid

Total disorderLots of empty space

DisorderSome spaceParticles closertogether

OrderParticles fixed in position

• Solids, Liquids, and Gases– Gases have no defined shape or defined volume

• Low density– Liquids flow and can be poured from one container to

another• Indefinite shape and takes on the shape of the container.

– Solids have a definite volume• Have a definite shape.

Review

• Matter On the Move jeopardy revision

• Complete revision questions page 4 (1 – 4). Check and review your answers

Changes in States of Matter• As temperature varies the particles change in

energy and distance apart• Changing states of matter is about changing

densities, pressures, temperatures, and other physical properties. The basic chemical structure does not change.

• Summarise the terms:– Melting point, Freezing point, Evaporate, Boiling

Point, Condensation Point, Volatile

Changes in States of Matter

Draw the image with the appropriate terms

Review

• Complete revision questions page 6 (5 – 7). Check and review your answers

Atomic theory

Sub atomic particles

Atomic theory

• The theory attempts to explain the microscopic structure of materials.

• All Matter is made up of Atoms

• Summarise the timeline (page 7) with the – date, scientist and major discovery.

Models of the Atom

a Historical Perspective

Aristotle

Early Greek Theories• 400 B.C. - Democritus thought matter could

not be divided indefinitely.

• 350 B.C - Aristotle modified an earlier theory that matter was made of four “elements”: earth, fire, water, air.

Democritus

• Aristotle was wrong. However, his theory persisted for 2000 years.

fire

air

water

earth

• This led to the idea of atoms in a void.

John Dalton• 1800 -Dalton proposed a modern atomic

modelbased on experimentation not on pure reason.

• All matter is made of atoms.• Atoms of an element are identical.• Each element has different atoms.• Atoms of different elements combine

in constant ratios to form compounds.• Atoms are rearranged in reactions.

• His ideas account for the law of conservation of mass (atoms are neither created nor destroyed) and the law of constant composition (elements combine in fixed ratios).

Dalton’s Postulates

1. Every element is composed of tiny particles called atoms

2. All atoms of a given element are identical1. Atoms of different elements have different properties

3. Atoms of an element are NOT changed into atoms ofanother element by chemical processes1. Matter can neither be created nor destroyed

4. Compounds are formed when atoms of more than oneelement combine

Dalton’s Laws1. The Law of Constant Composition:

“Any given compound always consists of the same atoms and the same ratio of atoms. For example, water always consists of oxygen and hydrogen atoms, and it is always 89 percent oxygen by mass and 11 percent hydrogen by mass”

2. The Law of Conservation of Mass:“The total mass of materials before and after a chemical reaction must be the same. For example, if we combine 89 grams of oxygen with 11 grams of hydrogen under the appropriate conditions, 100 grams of water will be produced—no more and no less.”

Dalton’s Laws3. The Law of Multiple Proportions:

“If two elements combine to form more than one compound,the masses of one of the elements that can combine with a given mass of the other element are related by factors of small wholenumbers”

For example, water has an oxygen-to-hydrogen mass ratio of 7.9:1. Hydrogen peroxide, another compound consisting of oxygen and hydrogen, has an oxygen-to-hydrogen mass ratio of 15.8:1. The ratio of these two ratios gives a small whole number.

Adding Electrons to the Model

1) Dalton’s “Billiard ball” model (1800-1900)Atoms are solid and indivisible.

2) Thompson “Plum pudding” model (1900)Negative electrons in a positive framework.

3) The Rutherford model (around 1910)Atoms are mostly empty space.Negative electrons orbit a positive nucleus.

Materials, when rubbed, can develop a charge difference. This electricity is called “cathode rays” when passed through an evacuated tube (demos). These rays have a small mass and are negative.Thompson noted that these negative subatomic particles were a fundamental part of all atoms.

Ernest Rutherford

Most particles passed through. So, atoms are mostly empty.

Some positive -particles deflected or bounced back!

Thus, a “nucleus” is positive & holds most of an atom’s mass.

Radioactive substance path of invisible

-particles

• Rutherford shot alpha () particles at gold foil.

Lead blockZinc sulfide screen Thin gold foil

• Rutherfords gold foil experiment

Bohr’s model

There are 2 types of spectra: continuous spectra & line spectra. It’s when electrons fall back down that they release a photon. These jumps down from “shell” to “shell” account for the line spectra seen in gas discharge tubes (through spectroscopes).

• Electrons orbit the nucleus in “shells”•Electrons can be bumped up to a higher

shell if hit by an electron or a photon of light.

The Structure of Atoms• Summarise and/or define:

• Nuclear model of the atom, Protons, Neutrons, Electrons, Sub-atomic particles, Ions, Elements, Atom, Atomic number, Mass number, Isotopic symbol, Isotopes, Atomic emission spectrum.

Atomic numbers, Mass numbers• There are 3 types of subatomic particles. We already know

about electrons (e–) & protons (p+). Neutrons (n0) were also shown to exist (1930s).

• They have: no charge, a mass similar to protons• Elements are often symbolized with their mass number and

atomic numberE.g. Oxygen: O16

8• These values are given on the periodic table.• For now, round the mass # to a whole number.• These numbers tell you a lot about atoms.

# of protons = # of electrons = atomic number # of neutrons = mass number – atomic number

• Calculate # of e–, n0, p+ for Ca, Ar, and Br.

3545358035Br

1822184018Ar

2020204020Ca

e–n0p+MassAtomic

Review• Complete the revision questions page 9 (8 – 11).

Check and review your answers

• What is the symbol for the Atomic number?• Z• What is the symbol for the Mass number?• A

Isotopes and Radioisotopes• Atoms of the same element that have different numbers

of neutrons are called isotopes.• Due to isotopes, mass #s are not round #s.• Li (6.9) is made up of both 6Li and 7Li.relative atomic mass

• Often, at least one isotope is unstable.• It breaks down, releasing radioactivity.• These types of isotopes are called radioisotopesQ- Sometimes an isotope is written without its atomic

number - e.g. 35S (or S-35). Q- Draw B-R diagrams for the two Li isotopes.A- The atomic # of an element doesn’t change Although

the number of neutrons can vary, atoms have definite numbers of protons.

http://www.gcsescience.com/a2-atomic-mass-number.htm

3 p+

3 n02e– 1e–

6Li 7Li

3 p+

4 n02e– 1e–

For more lessons, visit www.chalkbored.com

IsotopesIsotopes of Lithium illustration

http://www.chalkbored.com/

Isotopes• All atoms of a particular element have the same

number of protons.• Atoms with the same number of protons but a

different number of neutrons are called isotopes• Isotopes have similar chemical properties because

their electron structure is the same. They have different physical properties due to their different masses.

• List the three naturally occurring isotopes of oxygen.

Oxygen• Isotopes of Oxygen• There are three stable isotopes of oxygen that lead

to oxygen (O) having a standard atomic mass of 15.9994(3) amu

• Naturally occurring oxygen is composed of three stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant (99.762% natural abundance). Known oxygen isotopes range in mass number from 12 to 24

Review• Work through the sample problem on page 10• Complete the revision questions pages 10, 11 (12

– 17). Check and review your answers.

Atomic Emission Spectrum• Every element emits light if it is heated by passing

an electric discharge through its gas or vapour• This happens because the atoms of the element

absorb energy, then lose it and emit it as light.• Atomic emission spectrum consist of separate

lines of coloured light, each line of the spectrum corresponding to one particular frequency of light being given off by the atom: therefore each line corresponds to one exact amount of energy being emitted.

Bohr’s model

There are 2 types of spectra: continuous spectra & line spectra. It’s when electrons fall back down that they release a photon. These jumps down from “shell” to “shell” account for the line spectra seen in gas discharge tubes (through spectroscopes).

• Electrons orbit the nucleus in “shells”•Electrons can be bumped up to a higher

shell if hit by an electron or a photon of light.

3 p+

4 n02e– 1e–

Li shorthand

Bohr - Rutherford diagrams• Putting all this together, we get B-R diagrams• To draw them you must know the # of protons,

neutrons, and electrons (2,8,8,2 filling order)• Draw protons (p+), (n0) in circle (i.e. “nucleus”)• Draw electrons around in shells

2 p+

2 n0

He

3 p+

4 n0

Li

Draw Be, B, Al and shorthand diagrams for O, Na

11 p+12 n°

2e– 8e– 1e–

Na

8 p+8 n°

2e– 6e–

O

4 p+5 n°

Be

5 p+6 n°

B

13 p+14 n°

Al

Bohr’s energy levels• How does Bohr’s model explain the Atomic

Emission Spectrum.

• Define the terms: ground state, energy levels, excited state, photon

• Why does Bohr’s model not explain atoms more complex than Hydrogen?

• What is the Quantum mechanics model?

Electron Shells

• The regions of space surrounding the nucleus.

• The electron shells are labelled K, L, M, N and numbered 1, 2, 3, 4

• A definite energy level is associated with each shell (K – closest the nucleus – lowest energy). Therefore an electron has to gain energy to move away from the nucleus.

Electron Shells

• If an electron gains enough energy to completely leave the atom, the particle that is left is not longer neutral and called a positive ion.

• Explain how K can become K+. What is the difference in the protons and electrons when K becomes a positive ion?

Electron Configuration

• Electron configuration – arrangement of electrons in shells

• The maximum number of electrons that each shell can hold is 2n2 where n is the number or energy level


• Electron shells are filled in order from the nucleus (lowest energy level first – K)

• For the first 20 elements the outer shell never has more than 8 electrons

• The outer shell electrons mainly determine the chemical properties of an element.

Electron Configuration• Each electron has its own distinct energy, this

energy corresponds to the energy level it occupies

• Electrons can gain or lose energy, but that amount of energy gained or lost is a fixed amount of energy.

• This fixed amount of energy gained allows an electron to move to a higher energy level.


• Ground state – electrons occupy the lowest available oribitals.

• Excited state – unstable condition, electrons temporarily move to a higher energy level.

• When electrons are subject to stimuli such as heat, light, or electricity, electrons may absorb energy and temporarily move to a higher energy level.


• Chemical properties are based on the number of electrons in the outer energy level.

• Valence electrons are these outer electrons.

• Quantum theory – explains chemical behaviour of atoms.

• Quantum numbers – electrons are described as a set of four numbers


• First number describes the major energy level of the electron and is called the principle energy level.

• Principle energy levels have sublevels. There are as many sublevels as the number of that energy level.

• s is the first sublevel, p is the second, d is the third and f is the fourth.

• ie) 3s means third energy level and first sublevel


• Electron configuration – distribution of electrons in an atom.

• Electron configuration for oxygen would be 1s22s22p4

Review• Atomic structure on line multiple choice

• Periodic Table quiz

• atomic structure quiz

• Complete the revision questions pages 14, 15 (18 – 22). Check and review your answers.

http://www.gcsescience.com/q/qatstr.html

http://www.glencoe.com/qe/science.php?qi=688

http://www.quia.com/quiz/125691.html

Elements make compounds

Explosive experiment

• Goggles, bench mat, tongs, bunsen, lighter and magnesium.

• CAREFULLY put magnesium in flame.

•What energy is being released?-When magnesium is burned, energy is released as light.

•Is there a new substance being formed? -A new substance forms, it is white.

•Is this new substance lighter or heavier?

-This new substance is heavier as there are two different elements in the substance, they are magnesium and oxygen.

Making a compound

Elements make compounds

• When elements join to make a compound, energy is released and a new substance is formed.

• A word which means ‘energy released’ is exothermic.

• What do you think endothermic means?

Elements and Compounds• All matter is made up of combinations of

elements with atomic theory explaining the behaviour of these elements and their compounds

• An element is a substance that cannot be broken down into simpler substances because it is made up of only one type of atom.

• Elements can be grouped according to their physical and chemical properties as either metals or non-metals.

Elements, Compounds and Mixtures

• 2. Language of chemistry

• Define and give examples of:– An element– A compound – A mixture

• Mixtures and Pure Substances– A mixture has unlike parts and a composition

that varies from sample to sample– A heterogeneous mixture has physically

distinct parts with different properties.– A homogeneous mixture is the same

throughout the sample– Pure substances are substances with a fixed

composition

A classification scheme for matter.

– A physical change is a change that does not alter the identity of the matter. Physical changes are about energy and states of matter

– A chemical change is a change that does alter the identity of the matter. Chemical changes happen on a molecular level. ie burning sugar.

– A compound is a pure substance that can be decomposed by a chemical change into simpler substances with a fixed mass ratio

– An element is a pure substance which cannot be broken down into anything simpler by either physical or chemical means.

• Sugar (A) is a compound that can be easily decomposed to simpler substances by heating. (B) One of the simpler substances is the black element carbon, which cannot be further decomposed by chemical or physical means.

Isopropyl alcohol is a A. heterogeneous mixtureB. homogeneous mixtureC. pure substanceD. CompoundE. pure substance and compound

EXAMPLE

E

Naming Compounds

Elements and symbols that you should know:

1) Hydrogen2) Helium3) Lithium4) Beryllium5) Boron6) Carbon7) Nitrogen

8) Oxygen9) Fluorine10)Neon11)Sodium12)Magnesiu

m13)Aluminium14)Silicon

HHeLiBeBCN

OFNeNaMgAlSi

Elements and symbols that you should know:

15) Phosphorus

16) Sulphur17) Chlorine18) Argon19) Potassium20) Calcium

PSClArKCa

If two identical elements combine then the name doesn’t change.

.e.g. oxygen + oxygen oxygenThis happens with the following elements:1) H2

2) N2

3) O2

These elements always go around in pairs. For example, hydrogen looks like this:

1) Sodium + chlorine

2) Magnesium + fluorine

When two elements join the name ends with ____ide

e.g. Magnesium + oxygen magnesium oxide

When three or more elements combine and one of them is oxygen the ending is _____ite or

________ate

e.g. Copper + sulphur + oxygen Copper sulphate1) Calcium + carbon + oxygen

2) Potassium + carbon + oxygen

3) Sodium + sulphur + oxygen

Review

• Complete the revision questions pages17,18 (23 – 27)

Elements

• Discovery of Modern Elements– Antoine Lavoisier suggested that burning was

actually a chemical combination with oxygen.– Lavoisier realized that there needed to be a new

concept of elements, compounds, and chemical change.

– We now know that there are 89 naturally-occurring elements and at least 23 short-lived and artificially prepared.

• Priestley produced a gas (oxygen) by using sunlight to heat mercuric oxide kept in a closed container. The oxygen forced some of the mercury out of the jar as it was produced, increasing the volume about five times.

• Lavoisier heated a measured amount of mercury to form the red oxide of mercury. He measured the amount of oxygen removed from the jar and the amount of red oxide formed. When the reaction was reversed, he found the original amounts of mercury and oxygen.

Names of Elements– The first 103 elements have internationally

accepted names, which are derived from:• The compound or substance in which the element

was discovered• An unusual or identifying property of the element• Places, cities, and countries• Famous scientists• Greek mythology• Astronomical objects.

• Here are some of the symbols Dalton used for atoms of elements and molecules of compounds. He probably used a circle for each because, like the ancient Greeks, he thought of atoms as tiny, round hard spheres.

• The elements of aluminum, Iron, Oxygen, and Silicon make up about 88 percent of the earth's solid surface. Water on the surface and in the air as clouds and fog is made up of hydrogen and oxygen. The air is 99 percent nitrogen and oxygen. Hydrogen, oxygen, and carbon make up 97 percent of a person. Thus almost everything you see in this picture us made up of just six elements.

SymbolAtomic Mass

Atomic Number

Charge (if ion)

HHydrogen

1

1

Protons: 1Neutrons: 0Electrons: 1

NaSodium

23

11


Rhenium

Re186

75


Rhenium isotope

Re187

75


EXAMPLEHow many protons, neutrons and electrons are found in an atom of 133

55 CsAtomic number = protons and electrons

There are 55 protons and 55 electronsMass number = sum of protons and neutrons

133 – 55 = 78There are 78 neutrons

The Periodic Law

• Dmitri Medeleev gave us a functional scheme with which to classify elements.– Mendeleev’s scheme was based on chemical

properties of the elements.– It was noticed that the chemical properties of

elements increased in a periodic manner.– The periodicity of the elements was demonstrated

by Medeleev when he used the table to predict to occurrence and chemical properties of elements which had not yet been discovered.

• Mendeleev left blank spaces in his table when the properties of the elements above and below did not seem to match. The existence of unknown elements was predicted by Mendeleev on the basis of the blank spaces. When the unknown elements were discovered, it was found that Mendeleev had closely predicted the properties of the elements as well as their discovery.

• The Periodic Law– Similar physical and chemical properties

recur periodically when the elements are listed in order of increasing atomic number.

The Modern Periodic Table

• Introduction– The periodic table is made up of rows of elements

and columns.– An element is identified by its chemical symbol.– The number above the symbol is the atomic number– The number below the symbol is the rounded

atomic weight of the element.– A row is called a period– A column is called a group

Arrangement of the Periodic Table

• Elements with the same group number have the same number of electrons in the outer shell – valence electrons

• Q – which groups do the following elements below to? K, B, He, Cl, Ca (ie how many electrons in their outer shell?)


• The period number refers to the number of the outermost shell containing electrons.

• Q – which periods do the following elements belong to? Ca, Mg, Si, N, O, He

Arrangement of the Periodic Table - Groups

• Valence electrons mainly determine chemical reactivity. Elements in the same group usually have similar chemical properties. There is a progressive change in their physical properties.


• Group 1 – Alkali Metals– React with water to form alkaline solutions– Low melting points– Low boiling points– Densities so low they can float on water– So soft they can be cut with a knife– Very reactive and must be stored under oil to prevent

them reacting with oxygen and water vapour in the air – Eg – Na and K


• Group 2 – Alkaline Metals– They were first extracted from oxides found in

the earth’s crust– Less reactive than alkali metals – Eg Be, Mg

Arrangement of the Periodic Table – Groups

• Group 17 – Halogens– So reactive that they never occur freely in

nature– They occur combined with different metals to

form salts– Eg Cl, I


• Group 18 – Noble Gases– They do not react readily with other

substances

– The Noble Gases


• Groups 3 – 12 – Transition Metals– Hard metals – Usually have high melting point– Usually have high boiling point– Usually form coloured compounds

Arrangement of the Periodic Table - Periods

• Period number represents the number of occupied electron shells in the atoms of the elements in that group.

• Elements in the same period share a gradual change in their physical and chemical properties.

Arrangement of the Periodic Table - Periods

• Period 6 - Lanthanides or Rare Earth– Rare occurrence in nature

• Period 7 – Actinides– Radioactive elements


• Metal and Non-Metals– Diagonal step line starting at B– Separate metals from non-metals– Change from metallic to non-metallic is

gradual and some elements have characteristics of both metals and non-metals.


• Metalloids– Elements with combinations of metallic and

non-metallic properties– Eg Si and Ge have high melting points and

high boiling points (like metals), but have low densities and are brittle (like non-metals)

Trends in the Periodic Table• Across a period

1. Metallic character• Decreases across the table, while non-metallic character

increases• Elements in groups 1 and 2 are metals, group 18 are

gases

2. Atomic size• Generally decreases from metals to non-metals across a

period – electrons are being added to the same outer shell while number of protons in the nucleus in increasing (increases electrostatic attraction between electrons and nucleus, pulls outer electrons closer to the nucleus, reducing atomic radii

Trends in the Periodic Table• Across a period

1. Reactivity• Generally lowest in the middle of a period and increases at

either end (not including noble gases)• Eg period 3 reactivity with Hydrochloric acid• High Na Mg Al Low, Si non reactive, Low P S Cl

High

2. Electronegativity (electron attracting power of an atom)

• Increases from metals to non-metals across a period due to the electrons being increasingly attracted to the nucleus.

Trends in the Periodic Table• Down a Group

1. Metallic character• Increase down a group, while non-metallic

character decreases2. Atomic size

• Generally increases down a group as electrons are added to successive main shells and are therefore further away from the nucleus

Trends in the Periodic Table• Down a Group

1. Reactivity• Metals - Generally increases down a group • Eg reactivity with water – High K, Na, Li Low• Non-metals – Generally decreases down a group• Eg. Reactivity with water – High F, Cl, Br, I Low

2. Electronegativity• Generally decreases down a group – electrons are further

away from the nucleus and are ‘shielded’ from the attraction of the nucleus by the inner shell electrons

Trends in the Periodic Table• The Position of Hydrogen

– Sometimes in group 1, sometimes in group 17– Group 1 loses an electron– Group 17 – many of its properties are similar

to the Halogens – gains an electron when it reacts with some elements

Review

• Complete the revision questions pages 21,22 (28 – 34)

• (A) Periods of the periodic table, and (B) groups of the periodic table.

• Periodic Patterns– The chemical behavior of elements is

determined by its electron configuration– Energy levels are quantized so roughly

correspond to layers of electrons around the nucleus.

– A shell is all the electrons with the same value of n.• n is a row in the periodic table.

– Each period begins with a new outer electron shell

– Each period ends with a completely filled outer shell that has the maximum number of electrons for that shell.

– The number identifying the A families identifies the number of electrons in the outer shell, except helium

– The outer shell electrons are responsible for chemical reactions.

– Group A elements are called representative elements

– Group B elements are called transition elements.

• Chemical “Families”– IA are called alkali metals because the react with

water to from an alkaline solution– Group IIA are called the alkali earth metals

because they are reactive, but not as reactive as Group IA.• They are also soft metals like Earth.

– Group VIIA are the halogens• These need only one electron to fill their outer shell• They are very reactive.

– Group VIIIA are the noble gases as they have completely filled outer shells• They are almost non reactive.

Metal: Elements that are usually solids at room temperature. Most elements are metals.

Non-Metal: Elements in the upper right corner of the periodic Table. Their chemical and physical properties are different from metals.

Metalloid: Elements that lie on a diagonal line between the Metals and non-metals. Their chemical and physical properties are intermediate between the two.

– When an atom or molecule gain or loses an electron it becomes an ion.• A cation has lost an electron and therefore has a

positive charge• An anion has gained an electron and therefore

has a negative charge.

– Elements with 1, 2, or 3 electrons in their outer shell tend to lose electrons to fill their outer shell and become cations.• These are the metals which always tend to lose

electrons.– Elements with 5 to 7 electrons in their outer shell

tend to gain electrons to fill their outer shell and become anions.• These are the nonmetals which always tend to gain

electrons.– Semiconductors (metalloids) occur at the

dividing line between metals and nonmetals.

What would the charge be on a sodium ion?

EXAMPLE

Since sodium in in Group IA it is a metal and so would LOSE an electron

You can tell how many would be lost by the group numberGroup 1A elements lose 1 electron

So the charge would be +1Remember an electron is negatively charged. When you lose them atom becomes positively charged when you gain them it becomes negatively charged

How would you right the symbol for the sodium CATION?

EXAMPLE

Na+1

How many outer electrons does sodium have before it loses one?

It has 1…remember the group number!

Chapter One Review

• Solids, liquids, gases on line multiple choice• Periodic Table

• Complete the multiple choice questions page 24

• Consider each of the review questions 1 – 29

• Periodic table on line questions

http://www.gcsescience.com/q/qslg.html

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Chapter One

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