Modern Periodic Table

Modern Periodic Table

• Arranged by increasing Atomic Number

•Rows Called Periods– 7 Periods– Higher Number = more available

electron energy levels

1234567

Horizontal Rows Called Periods 1-7

Groups•Vertical Columns Called

Groups or “families”.

• Elements in same Group have similar chemical properties– All have same # of valence

electrons

18 Groups (Vertical Columns)

Periodic Law

• Pattern of repeating properties of elements in groups

17

Cl

Chlorine35.453

4 pieces of information in any square

Atomic Number

Element symbol

Element Name

Average atomic Massin amu

Classes of Elements

• Atomic Numbers 1-92 occur naturally

• Atomic numbers 93 and higher do not occur naturally– Synthetic (man made)

3 General Classes of Elements

•1. Metals: Good conductors of heat & electricity– Majority of Elements– On left side bold staircase– Most are malleable (hammered

w/out shattering) & ductile (drawn into wires)

– Most are solid except mercury (liquid)

3 General Classes of Elements

•2. Nonmetals: poor conductors of heat & electricity– Properties opposite of metals– To the right of bold staircase– Many are gases; solid ones are

brittle (break when hit)

•3. Metalloids: Properties fall in between metals & nonmetals– Found on bold staircase– Ability to conduct electricity varies

with temperature– Only conduct electricity at high

temps.– Called semiconductors; used in

computer chips

• Ex: Silicon

Metals Nonmetals

Metalloi

ds

Periodic Trends

• From left to right across a period:

• Elements become less metallic & more nonmetallic