Ions

Remember…  Atomic Number is the number of protons in an atom.  The number of protons equal the number of electrons in a neutral atom.  Atomic Mass is the sum of the protons and neutrons in an atom.  6p + + 6n 0 = 12 (atomic mass of carbon)

Ions  A charged entity.  This occurs if the number of electrons do not equal the number of protons.  This only occurs when an electron is added or removed from an atom.  The number of protons never change. An atom will gain or lose electrons to become more stable.

Cations  ion with a positive charge.  If a neutral atom loses one or more electron it becomes a cation. Na 11 protons 11 electrons Na + 11 protons 10 electrons

Anions  ion with a negative charge.  If a neutral atom gains one or more electrons it becomes an anion. Cl 17 protons 17 electrons Cl - 17 protons 18 electrons

Atomic Radii Li Na K Rb Cs Cl S P Si Al Br Se As Ge Ga I Te SbSn In Tl Pb Bi Mg Ca Sr Ba Be F O N C B IA IIA IIIA IVA VA VIA VIIA = 1 Angstrom IA IIA IIIA IVA VA VIA VIIA = 1 Angstrom Li 1+ Be 2+ Na 1+ Mg 2+ Ba 2+ Sr 2+ Ca 2+ K 1+ Rb 1+ Cs 1+ Cl 1- N 3- O 2- F 1- S 2- Se 2- Br 1- Te 2- I 1- Al 3+ Ga 3+ In 3+ Tl 3+ Ionic Radii

A monatomic ion contains only one atom A polyatomic ion contains more than one atom 2.5 Na +, Cl -, Ca 2+, O 2-, Al 3+, N 3- OH -, CN -, NH 4 +, NO 3 -

Oxidation State of Elements Se 2- Te Al 3+ Zn 2+ Ag 1+ N 3- O 2- F 1- Cl 1- S 2- Br 1- I 1- Period Be 2+ Na + K+K+ Rb + Cs + Ba 2+ H+H+ Li + Ca 2+ Sr 2+ Mg 2+ Group NOBLEGASESNOBLEGASES Transition metals

Some Polyatomic Ions 2.7

PREDICTING ION CHARGES In general  metals (Mg) lose electrons ---> cations (Mg 2+ ) ons (F - )  nonmetals (F) gain electrons ---> anions (F - )

Learning Check – Counting State the number of protons, neutrons, and electrons in each of these ions. 39 K + 16 O -241 Ca #p + ___________________ #n o ___________________ #e - ___________________

How would you right the symbol for the sodium CATION? EXAMPLE Na +1 How many outer electrons does sodium have before it loses one? It has 1…remember the group number!

ionic compounds consist of a cation and an anion the sum of the charges on the cation and anion in each formula unit must equal zero The ionic compound NaCl 2.6

Formula of Ionic Compounds Al 2 O x +3 = +63 x -2 = -6 Al 3+ O 2- CaBr 2 1 x +2 = +22 x -1 = -2 Ca 2+ Br - Na 2 CO 3 1 x +2 = +21 x -2 = -2 Na + CO 3 2-

1. sodium chloride 2. calcium oxide 3. potassium hydroxide 4. magnesium sulphide 5. copper(II) carbonate 6. aluminium oxide