Atoms and The Periodic Table

Learning Targets:1.Describe atoms2.Use the Periodic Table

Atoms

What are atoms? Atoms are the basic building blocks of matter

that make up everyday objects. A desk, the air, even you are made up of atoms!

There are 90 naturally occurring kinds of atoms. Scientists in labs have been able to make about 25 more.

Structure of Atoms

All atoms are made of a

•nucleus, or center

•surrounded by orbits of electrons

The nucleus is made up of 2 kindsof particles:•Protons-which have a positive charge. The number of protons determines what element you have.

•Neutrons-- which have no charge. The number of neutrons usually matches the number of protons, but isotopes of an element may have different numbers of neutrons.

Around the nucleus of an atom, are orbits of electrons.

Electrons are very small, negatively charged particles. Their negative charge attracts them to the positively charged protons in the neucleus.

With your partner, describe these 3 particles that make up all atoms:ElectronProtonNeutron

Electron orbits exist in several shells or energy

levels.

First energy level

Secondenergy level

Scientists often illustrate the electron arrangement

with a drawing called a Bohr diagram. This shows the

placement of the electrons into their energy levels.

Atoms like to have their outside energy level full. If

it is not, they are more likely to react with other atoms.

Elements react when they give, take or share electrons from other elements.

Water is formed when 2 hydrogen atoms share electons with

1 atom of oxygen

Discuss with your partner:1.How are electrons arranged?2.What does a Bohr diagram show you?3.What is likely to happen if elements DON’T have their outer electron level full?4.What happens when one atom reacts with another atom?

What would you expect different elements to be like?

Which elements are most likely to react? What will they be likely to react with?

Clues to the answers to these questions can be found

in a tool called

THE PERIODIC TABLE.

The Periodic TableOrganization of the Elements

Search for Order 1750 only 17 elements known 1789 Antoine Lavoisier grouped known

elements (4 groups) Metals Non-metals Gases Earths

Next 80 yrs scientists looked for better way to classify known elements

Mendeleev’s Periodic Table 1869….Dmitri Mendeleev

(Russian teacher and chemist) organized known elements while playing solitaire Made deck of cards with elements Listed name, mass and properties

Paid attention to how elements reacted in chemical reactions

Mendeleev’s Periodic Table

Strategy for organization: What did he look at?

chemical propertiesphysical propertiesatomic massdensitycolormelting pointValence electrons (sec 5.3)

Mendeleev’s Proposal

Elements arranged in rows based on increasing mass.

Elements with similar properties are in same column.

Chart was a Periodic Table - arrangement of elements in columns based on a set of properties that repeat.

Mendeleev’s Prediction Table incomplete–

elements not yet discovered

Left spaces in table for undiscovered elements

Good models allow for predictions to be made based on model

Used properties of nearby elements to predict properties of unknown elements

He called this element eka-Aluminum.

Later it was renamed Gallium after its

discovery in 1875

Evidence Supporting Mendeleev’s Table

Close match between Mendeleev’s predictions and the actual properties of new elements showed how useful table was. Ex. Discovery of: Aluminum, Gallium, Scandium,

and Germanium

http://www.iteachbio.com/Chemistry/Chemistry/The%20Periodic%20Table.mov

Section 5.2The Modern Periodic

TableThe Elements by Tom Lehrer

YOU NEED 3 DIFFERENT YOU NEED 3 DIFFERENT COLORED PENCILSCOLORED PENCILS

The Modern Periodic Table

“Periodic” - Repeating patterns

Listed in order of increasing number of protons (atomic #)

Properties of elements repeat Periodic Law-Periodic Law- when elements arranged by

increasing number of protons, properties repeat in pattern

Columns in the Periodic Table

-vertical (up & down) -called groups or families-#ed 1-18 or 1A through 8A-elements in same family have

similar properties

Rows in the Periodic Table

-horizontal (left – right)-called a period-properties change greatly across

period-first element in period is very active

metal-last element in most periods is noble

gas-7 periods (number them on your

periodic table)

Discuss with your partner:

Why is a chemists chart called a PERIODIC table

—what does periodic mean?

Element Key

Important information about an element is given in each square of the periodic table: its atomic number chemical symbol element name average atomic mass

6

CCarbon12.01

For example:Carbon has atomic # 6 (or has 6 protons), an average atomic mass of 12.01 and a symbol of C

What are 4 important pieces of information each

square of the Periodic Table gives you about its

element?

Metals Most solids (Hg is liquid) Luster – shiny. Ductile – drawn into thin

wires. Malleable – hammered into

sheets. Conductors of heat and

electricity. Include transition metals –

“bridge” between elements on left & right of table

Non-Metals

Properties are generally opposite of metals

Poor conductors of heat and electricity

Low boiling points Many are gases at room temperature Solid, non-metals are brittle (break

easily) Chemical properties vary

Metalloids

stair-step pattern Have properties similar to

metals and non-metals Ability to conduct heat and

electricity varies with temp Better than non-metals but

not metals

Section 5.3Representative Groups

The Elements

Hip Hop Classroom

What are Valence electrons?

outermost e-’s Responsible for chem props Elements in same group… same # of VE ALL atoms want full outer energy level (usually 8 VE) To get full outer energy level, some elements:

lose e- (metals) gain e- (non-metals) share electrons (some non-metals & metalloids)

1.What are valence electrons?

2.Why are they important?

Introducing the ten major

groups (families) on the modern Periodic

Table:

Alkali Metals- 1 valence electron (VE)- soft, silver-white, shiny

metals- never found pure - most reactive metals- Reactivity increases

down group

- Hydrogen is not a member of this

group. - It is not a metal.

-

reactivity increases

potassium

Label the Alkali Metals to your PT

Alkaline Earth Metals

- 2 VE- not as reactive as

alkali metals- often mixed with

Al- forms strong/light

weight alloys

magnesium

Alkaline Earth Metals

Magnesium Used to make steel

(light metal w/o losing strength)

photosynthesis (chlorophyll)

Calcium bones & teeth Chalk, limestone, pearls,

plaster

Label the Alkaline Earth Metals to your PT

Boron Family

Boron Hard/brittle never found

pure in nature in borax...used

to make detergents & cosmetics

-3 VE

Boron FamilyAluminum most

abundant metal in earth’s crust

important metal for industry light, strong,

slow to corrode

13

AlAluminu

m26.98

Aluminum

Label the Boron Family on your PT

Carbon Family- 4 VE- Can gain 4 e-,

lose 4 e-, or share e-

- Most compounds in body contain C

- Si 2nd most abundant element in Earth’s crust

- Si used to tip saw blades

silicon

Label the Carbon Family on your PT

Nitrogen Family- 5 VE - Tend to gain 3 e-- N and P used in

fertilizers- P on tips of

matches

Arsenic

Label the Nitrogen Family on your PT

Oxygen Family- 6 VE- Tend to gain 2 e-- O very abundant

element- S used in fertilizers- O needed for digestion

sulfur

Label the Oxygen Family on your PT

Halogen Family (“salt-former”)

-7 VE-most active nonmetals-never found pure in nature-react with alkali metals

easily (forms salts)-F most active halogen

Halogens cont…

F compounds in toothpasteCl kills bacteriaI keeps thyroid gland

working properly

bromine

Label the Halogen Group on your Periodic TableLabel the Halogen Group on your Periodic Table

The Noble Gases (Inert Gases)

- non-reactive- outermost e-

shell is full (8 VE)

- In “neon” lights-in earth’s

atmosphere (less than 1%)

Neon

Label the Noble Gases on your Periodic TableLabel the Noble Gases on your Periodic Table

Discuss:1.What are chemical “families”?2.How are they different from periods?

Transition Metals Almost all solids at room temp (Hg exception) ductile, malleable, conductors VE varies Less Reactive than Groups 1 & 2 Fe, Co, and Ni produce magnetic field

mercury

Label the Transition Metals on your periodic tableLabel the Transition Metals on your periodic table

Rare Earth ElementsLanthanide series (period 6)Actinide Series (period 7)

Some radioactive Separated from table to make easy to

read/print silver, silvery-white, or gray metals. Conduct electricity

uranium

Label the Lanthanide Series on your PT

Label the Actinide Series on your PT

You may watch more videos about the elements at:

http://www.periodicvideos.com/

or sing along at: http://www.youtube.com/watch?v=zGM-wSKFBpo&feature=related

hip hop classroom

elemental funkiness - Mark Rosengarten

Did you reach our learning targets?

1.Describe atoms2.Use the Periodic Table

Use the table to describe oxygen.