Periodic Table of Elements

Pages 124-167Ch.4.1, 4.2, 4.3, 4.4 and 5.1

Dmitri Mendeleev

• He recognized patterns in the element’s approximate atomic masses and their ability to bond with other elements.

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Periodic Table

• Based on atomic masses and their ability to bond with other elements, Mendeleev constructed the first periodic Table.

The Atom

• Nucleus: The core of the atom that contains two different subatomic particles.

The Atom cont…

• Protons: Have a positive charge.

• The number of protons equals the number of electrons.

The Atom cont…

• Neutrons: Have no Charge.

The Atom cont…

• Electrons Negative charge.

• .

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Atomic Numbers, Symbols and Mass• Atomic

number is the smaller number and the number of protons in the nucleus.

47

AgSilver

107.868

Element Symbol

Element Name

Atomic mass is all the protons and neutrons added together.

How to calculate # of neutrons

• Atomic mass - Atomic number = # of neutrons

This element is Nitrogen. Its mass is 14. So atomic # of 7, minus atomic mass of 14, equals 7 neutrons.

Count the number of protons. What element is it?

How to Calculate Number of Electrons

• The number of electrons equal the number of protons.

7 electrons

7 protons

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Isotopes

• When atoms of the same element have a different number of neutrons

Valence Electrons

• The electrons on the outermost ring or energy level that can be shared or transferred with other atoms to make compounds.

Valence Electrons and Bonding (ch. 5.1 pgs. 176-182)The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms.

Take out a piece of paper, stand up

and stretch

Without any talking, use your notes and book to answer the following

questions.• What is inside an atom? (pg. 126-127)

• What information does the periodic table tell us? (pg. 132-133)

• What are the columns called? What are the rows called? (pg. 136)

• How do elements relate to each other in rows? What about columns? (pgs. 136)

Groups –Familieselements in a group have verysimilar characteristicsi.e. bonding, reactivity, valence electrons

Periods- elements in a period are not alike, but gradually change as you move from left to right.

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METALS

•Almost 75% of all elements are classified as metals.

Properties of Metals• Conductors: Metals are good at conducting electricity.

• Malleable: Ability to bend or pound into shapes.

Properties of Metals

•Ductile: Pull or stretch into wire.

•Many are shiny, hard and magnetic.

Properties of Metals cont…

• Reactivity: Ability to react and combine with other elements. Some are more reactive than others. Sodium (Na) and potassium (K) are some of the most reactive metals.

Alloys

•Metals can easily combine into different mixtures of elements.

Examples of alloys• Steel: Fe+C+Cr+V• Bronze: Sn+Cu• Brass: Cu+Zn• White Gold: Ag+Au+Zn+Cu

• Yellow gold: Au+Cu+Ni+Zn

ALKALI METALS-Group 1

•So reactive that they are never found isolated in nature, only combined with other elements.

ALKALI METALS-Group 1

Characteristics Properties:

• Soft

• Shiny

• One valance: electron makes them very reactive.

Write down the following:

Reactivity of Hydrogen demo• Purpose: To isolate and observe the

reactivity of an alkali element: H (hydrogen).

• Materials: 250mL flask, mossy zinc, hydrochloric acid, balloon, string, funnel, meter stick, and matches.

• Place enough zinc into the flask to cover the bottom.

• Place the funnel on the mouth of the flask.• Pour enough HCL into the flask to cover the

zinc (about 2cm high)• Quickly, but carefully remove the funnel and

place the balloon over he mouth of the flask.• Let the gas fill the balloon.• Tie the string around the balloon and remove

the balloon from the flask.• Tie the balloon to a safe place.• Attach a match to the end of a meter stick and

light the balloon with the lit match.

Alkaline Earth Metals

• Group 2 metals.

• Very reactive, not as reactive as alkali metals due to having one more valence electron.

• Ca: important for bones.

TRANSITION METALS

• All are good conductors of electricity.

• Fairly stable.

• Fe : Iron is important for carrying oxygen in your blood.

Lanthinides and Actinides

• AKA Rare Earth Elements.

• Placed at the bottom of the table for convenience.

• They are in Periods 6 and 7.

Metalloids

Have some properties of both metals and nonmetals.

They are located on the zigzag line between the metals and the nonmetals.

Physical Properties:

•Can be good at conducting electricity, therefore some are used as computer chips such as Si and Ge.

Non-metals•Non metals lack properties of metals.

•They are on the right side of the periodic table.

•Non metals usually react with metals to make compounds.

•In general, metals give up electrons to non-metals.

Fe

O

Fe2O3 = Iron Oxide = Rust

Predicting Reactions

• Elements become more stable as they gain more valence electrons.

• As a result, atoms will gain, lose or share electrons to form compounds so that they have 8 valence electrons or a full shell.

• This is called the Octet Rule. However there are many exceptions, but this is an easy way to predict common reactions.

Atoms are “happy” when they have either only 2 valence electrons (He and H) or 8 electrons.

Families of Non-metals

• Carbon Family is group 14 and is the only non-metal in that group and is found in all living things.

Carbon needs 4e

Oxygen needs 2e 2 O on 1

C makes…

CO2

Families of Non-metals

Nitrogen Family is group 15 and Nitrogen makes up 78% of the earth’s atmosphere.

Nitrogen needs 3e

Hydrogen can give

1e 3 H on 1 N

makes…

NH3

Families of Non-metals

Oxygen family is group 16 and oxygen makes up approximately 20% of the earth’s atmosphere.

Oxygen needs 2e

Magnesium can give 2e 1 Mg on

1 O makes…

MgO

• The Halogen family is group 17. Each element has 7 electrons, therefore it commonly takes one electron away from group one metals to make compounds.

Families of Non-metals

Chlorine needs 1e

Potassium can give

1e 1 K on 1 Cl

makes…

KCl

• The Noble Gases are group 18. They have 8 valence electrons, therefore they are very stable and non-reactive.

Families of Non-metals

Hydrogen

• Not a part of group 1.

• Generally found as H2

•It doesn’t fit into any other family because it is so different from all other elements.

The Sun and Nuclear Fusion• How does the sun produce energy?

• During nuclear fusion, two atomic nuclei collide and fuse.

Chemical compositions of Stars:

Each element absorbs different wavelengths of light and shows up as lines on a spectrum.

Temperature: Stars at different temperatures produce different line spectra.

Star Spectrums• Astronomers can use line spectrums to identify

the chemical elements in a star. Each element produces a characteristic pattern of spectral lines.

The Hertzsprung-Russell Diagram

• Astronomers use H-R diagrams to classify stars and to understand how stars change over time.

The Earth’s Seasons• Equinox: Two days of the year half

way between the solstice, the earth’s axis is neither pointed away or toward the sun. The daylight hours are equal to the nighttime hours.

• Vernal Equinox: or Spring equinox is on March 21st

• Autumnal Equinox: is September 23rd.

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