periodic table & bonding. all elements have a neutral (zero) charge off the periodic table....

Periodic Table & Bonding

• ALL elements have a neutral (zero) charge off the periodic table.

Example: Sodium (element 11)Na 11 protons (11+) {atomic number}

11 electrons (11-)

0 charge overall

** Just as a reminder: Neutrons can be calculated as well,if needed. (Atomic mass – atomic number)

23 - 11 = 12 neutrons

ELEMENTS are pure substances.

Examples: Calcium (Ca), Sodium (Na), Chlorine (Cl), Oxygen (O),

Nitrogen (N)

COMPOUNDS are combinations of elements.

To do that, elements become ions that contain charges, then they are attracted due to opposite charges.

For example:

Na+1 Cl-1 [Charges must equal zero!]

NaCl (table salt is produced)

OR

Ca+2 Cl-1 [Charges must equal zero!]

Cl-1

CaCl2 The small number indicates how MANY were needed

Q: So, how do I know the charges (oxidation numbers) of the ions?

A: By looking at their location on the periodic table, their oxidations are evident.

Let’s see how that works

Here are the oxidations for the main columns of the periodic table:

+1 +2 -3 -2 -1 0

Here are a few more examples:

Ca+2 O-2 so…….. CaO

Na+1 O-2 so …… Na2O

Ca+2 N-3 so ……. Ca3N2

(hint: mathematically they both go into 6)

Now you try:

Li Cl produces ??????

Na N produces ??????

Mg Br produces ??????

Here are the answers:

LiCl (charges already equal zero)

Na3N (It takes 3 Na to equal the N)

MgBr2 (It takes 2 Br to equal the Mg)

** Remember:

All charges came from their location on the chart.