Chapter 3Chapter 3

IONS and The Periodic Table

EXIT

IonsIons Atoms acquire a charge by gaining or losing electrons

– not protons!!

Ion Charge = # protons – # electrons

ions with a + charge are called cations– more protons than electrons– form by losing electrons

ions with a – charge are called anions– more electrons than protons– form by gaining electrons

2

EXIT

Atomic Structures of IonsAtomic Structures of Ions

Metals form cations

For each positive charge the ion has 1 less electron than the neutral atom– Na atom = 11 p+ and 11 e-, Na+ ion = 11 p+ and 10 e-

– Ca atom = 20 p+ and 20 e-, Ca2+ ion = 20 p+ and 18 e-

Cations are named the same as the metalsodium Na Na+ + 1e- sodium ioncalcium Ca Ca2+ + 2e- calcium ion

The charge on a cation can be determined from the Group number on the Periodic Table– Group 1A +1, Group 2A +2, (Al, Ga, In) +3

3

EXIT

Atomic Structures of IonsAtomic Structures of Ions

Nonmetals form anions

For each negative charge the ion has 1 more electron than the neutral atom– F = 9 e-, F- = 10 e-

– P = 15 e-, P3- = 18 e-

Anions are named by changing the ending of the name to -idefluorine F + 1e- F- fluoride ionoxygen O + 2e- O2- oxide ion

The charge on an anion can be determined from the Group number on the Periodic Table– Group 7A -1, Group 6A -2

4

EXIT5

Li+1

Na+1

K+1

Rb+1

Cs+1

Be+2

Mg+2

Ca+2

Sr+2

Ba+2

Al+3

Ga+3

In+3

O-2

S-2

Se-2

Te-2

F-1

Cl-1

Br-1

I-1

N-3

P-3

As-3

1

2 13 171615

Zn+2

Cd+2Ag+1

18Common Ions