Periodic Table

A Guided Tour of the

Periodic Table

Organization

• Arranged based on

proton number

• Groups similar

elements together

• Easier to predict

properties

• Elements represented

by symbols

Electronic Arrangement

• Horizontal rows are called periods
• Protons and electrons increase by one as

you go L-R

• Location in periodic table linked to orbitals

Groups

• Groups are columns in the

PT

• Also called families
• Have same number of

valence electrons in a family

• Share similar chemical

properties

Ions

• Some atoms do not have filled outermost

energy levels

• To fill outermost levels, atom loses or

gains electrons

• Ion – «an atom that has a charge b/c of

losing or gaining electrons»

• Loss of electrons results in positive ion

(cation)

• Gaining an electron results in negative ion

(anion)

Ion Formation

• Lithium has 3 protons and 3 electrons

• 3+ and 3- = zero
• Lose an electron
• 3+ and 2- = +1

• Fluorine has 9 protons and 9 electrons

• 9+ and 9- = zero
• Gain an electron
• 9+ and 10- = -1

Squares of the Periodic Table

• Atomic Number

– (# of protons)

• Symbol
• Name
• Atomic Mass

– (protons + neutrons)

Atomic Number

• Number of protons
• Also number of

electrons

• Each element has

different atomic number

• Atomic number never

changes!

Element symbols you must learn

Symbols that are the first letter of the element name:

P -phosphorus
I -iodine
N -nitrogen
C -carbon
H -hydrogen
O -oxygen
F -fluorine
B -boron
S -sulfur

More element symbols you must

learn

Symbols that are from the first two or first and third

letter of the name:

He-helium

Ca-calcium

Li-lithium

Cr-chromium

Be-beryllium

Mn-manganese

Ne-neon

Co-cobalt

Mg-magnesium

Ni-nickel

Al-aluminum

Zn-zinc

Si-silicon

Br-bromine

Cl-chlorine

Sr-strontium

Even More element symbols

you must learn!

These symbols are from the Latin form of the

element name:

Na-sodium
(Na, I don’t need any sodium because of my

diet.)

K-potassium
(Aunt K loves potassium!)

Even More element symbols

you must learn

Fe-iron
(The Santa Fe railroad is made of iron.)
Cu-copper
(Cu later copper!)
Ag-silver
(The Ag barn is made of silver?)

The last ones!

•

Sn-tin
(Use Snips to cut tin.)
Au-gold
(Au, got any gold?)
Hg-mercury
(That old Hg has mercury in her veins.)
Pb-lead
(My Pb sandwich has lead in it!)

Mass Number

• Also called atomic mass number or atomic

mass

• Found by adding number of protons and

neutrons

• Can change due to differing # of neutrons
• Represented by decimal number b/c it is

the average of the isotopes of that element

Isotopes

• Different versions of an atom
• Has same number of protons

and electrons, but different
number of neutrons

• Affects mass
• Isotopes share chemical

properties

Summary

• Protons never change number

• Electrons can be lost or gained

• Neutrons can be gained

Calculating neutrons

• If protons + neutrons =

atomic mass

• Then atomic mass –

protons = neutrons

Calculating neutrons practice

• Atomic mass=37
• # Protons =17
• # Neutrons = ???

Atomic mass=35
# Protons =17
# Neutrons = ???

Time to think!

• Horizontal rows are called _______.
• Protons and ______ increase by one as you go L-R

in the periodic table.

• Arsenic has an atomic mass of 75 and an atomic

number of 33. How many neutrons does As have?

• Family is another name for a ________.
• A different version of an atom that has a different

number of neutrons is called a _____.