Physical Science

Ch 5 Periodic Table

Standards• Relate properties of atoms and their position in the

periodic table to the arrangement of their electrons.• Differentiate among conductors, semiconductors, and

insulators.• Describe how scientific inferences are drawn from

scientific observations & provide examples.• Discuss effects of technology on environmental quality.• Predict human impact on environmental systems .• Weigh alternative strategies for solving specific societal

problems by comparing human, economic, and environmental aspects.

Chapter assignments from the book:

• 139/26-28

• 140/1-8

• 150/107

• 155/1-8

• 164/1-4

Mendeleev

1. Placed elements in order by mass2. Elements with similar properties were in

the same column3. His periodic table could be used to

predict properties of newly discovered elements

4. He predicted an unknown element would have properties similar to aluminum and called it eka-aluminum

• The Periodic Table of the Elements is a way to arrange the elements to show a large amount of information and organization.

• The Periodic Table is NOW arranged in order of increasing atomic number.

Periodic Table Organization

1. As you read across the chart from right to left, a row of elements is a Period.

2. As you read down the chart from top to bottom, a column of elements is a Group or Family

3. Elements in a column have similar properties

Group IA alkali metals

Group IIAalkaline earth Metals

Group IIIB-IIBtransition metals

Inner Transition Metals

Lanthanide Series - also called the rare earth elements.

Actinide Series

Group VIIIA noble gases

or inert gases

Group VIIA - halogens

Bright Green - nonmetals

Purple - metalloids or

semiconductors

Light Blue - other metals

In the periodic table

• A set of properties repeats from row to row

• The atomic number increases from left to right

• The atomic number is the number of protons in an atom of an element

• The atomic number is equal to the number of electrons when an atom is neutral

http://periodic.lanl.gov/default.htm

• Periodic Table of the elements

• Los Alamos

• Atomic Mass - the mass of one mole of an atom. (One mole is 6.02 x 1023 atoms)

• Mass Number (the atomic mass number rounded) - the total amount of protons and neutrons in the nucleus of an atom

• Example: Tantalum, atomic # 73• 180.948 is the atomic mass• 181 is the p+n total• Subtract 73 p and it has 108 neutrons• Now you try with Zinc• 65.39 65P+N - 30P = 35N

Electrons

• Are found in energy levels (or orbitals) around the nucleus.

• The period an element is in indicates how many energy levels in which an atom has electrons (see long periodic chart given to you)

• Ca has 2 8 8 2

• Al has 2 8 3

Energy Level # of orbitals Max # of e’s

1 1 (En. Lev.

Squared) S2 (2 x # of orbitals)

2 4 P 8

3 9 D 18

4 16 F 32

Atomic Mass

• The weighted average of the masses of an element’s isotopes found in nature.

• Atomic mass unit - one twelfth of the mass of a carbon -12 atom (Carbon – 12 is the Standard Mass)

• The unit is an amu (1/12 of the mass of C-12.)

Reactivity Patterns

• Reactivity is closely related to the number of VALENCE electrons in the atoms of an element.– Most reactive metal group is IA with 1 valence e– Most reactive nonmetal group is VIIA with 7 valence

e’s

• On the metal side of the Periodic Chart, going down a group, the elements get more reactive. Cs > Na (This is determined by how they behave when placed in water)

• On the nonmetal side, going up, the elements get more reactive. F > At

• Reactive metals EASILY lose valence electrons (1 or 2 to have 8 in outer E level)

• Reactive nonmentals EASILY take valence electrons (to have 8 in outer E level.

Most Reactive

Metals

Most reactive

NonMetalsHighly reactive elements are stored in containers containing oils or argon

More on Reactivity

• Examples:

• Ge would be a better electrical conductor that Se (Ge more metallic than Se)

• Two highly reactive elements in Period 3 are the metal Na and the nonmetal Cl

Most metals are…

• Good conductors of heat and electricity

• Malleable

• Ductile

Most nonmetals are…

• Poor conductors of heat and electricity

• Brittle

Etc.

• Some highly reactive metals are stored in argon

• Sodium is found in nature only in compounds (highly reactive)

• Carbon is found in most compounds in your body except water