1. The Elemental Dating Game
Ionic & Molecular Compounds

2. Compounds
compounds are chemical substances made up of 2 or more elements that are chemically bonded together in fixed proportions
compounds are formed by chemical reactions
elements form compounds to be more stable
chemical bonds form when the atoms of an element gain, loose or share electrons
ionic compounds - electrons are transferred between atoms
molecular compound – formed if electrons are shared between atoms

3. all compounds have a name AND a chemical formula
e.g. water is H20
e.g. table salt (sodium chloride) is NaCl
e.g. baking soda (sodium bicarbonate) is NaHCO3
the chemical formula uses letters and numbers to represent the composition of the compound
e.g. water is made up of 2 atoms of hydrogen combined with 1 atom of oxygen

4. e.g. H2O(l) is liquid water NaCl(aq) is salt dissolved in water
we can show the state of the compound at room temperature is also shown in the formula
s = solid
l = liquid
g = gas
aq = aqueous (dissolved… in solution)
e.g. H2O(l) is liquid water
NaCl(aq) is salt dissolved in water

5. Ionic Compounds atoms of element are neutral
(# protons = # electrons)
when an atom gains or looses an electron it becomes a negatively or positively charged ION
electrons are transferred from metal atom leaving a + charged ion... to the non metal atom leaving a – charged ion
Cl–
Na+

6. → + ionic compounds involve metals AND non metals
metallic ions have a + charge
non metallic ions have a – charge
ionic compounds form because there is an attraction between ions which have opposite charges
e.g. NaCl – sodium chloride → +
Cl–
Na+
NaCl

7. the ionic charge for each element is shown on the periodic table
ionic charges follow a predictable patterns in family groups

8. Characteristics of Ionic Compounds
made of metal & non metal
bonds formed by transfer of electrons
metal ion is positive… non-metal ion is negative
bonds are very strong bond
until in water and then become very weak (compound dissolves)
solid at room temperature
good conductors of electricity (in solution)
ionic compounds used for batteries!

9. Naming Ionic Compounds
metal is first… then non metal
just say the metal’s name
eg. Na is sodium
take the non metal’s name and change last 3 (or 4) letters to “ide”
e.g. Cl is chlorine… changed to chloride
… so NaCl is called sodium chloride

10. Some More Examples CaO: calcium and oxygen → calcium oxide
Mg3N2: magnesium and nitrogen → magnesium nitride
Al2O3: aluminum and oxygen → aluminum oxide
KI: potassium and iodine → potassium iodide
BaF2: barium and fluorine → barium fluoride

11. What is the Chemical Formula?
look at the name of the 1st element (metal)… and write down its symbol
e.g. sodium chloride – the 1st element is sodium or Na
look at the name of the 2nd element (non metal) → you should be able to tell what it is even with the “ide” ending… and write down its symbol
e.g. sodium chloride – the 2nd element is chlorine or Cl
then you need to balance the charges to “0”

12. Balancing Charges the “net” charge of a compound must be zero
e.g. Na+ + Cl- → NaCl
–1 → 0
the number of atoms of an element must be correct to create a balanced charge
e.g. Ca Cl- → CaCl2
(–1) → 0

13. the chemical formula will show how many atoms of each element are present in the compound
e.g. NaCl has 1 atom of Na and 1 atom of Cl
e.g. CaCl2 has 1 atom of Ca and 2 atoms of Cl
NaCl
CaCl2

14. More than One Ion Charge?
some elements like Fe, Cu and Pb can form more than one ion charge
to show which ion is present in a compound a Roman numeral is added to the compound name
e.g.
FeO is called iron (II) oxide because Fe+2 is present:
Fe+2 + O-2 → FeO
and
Fe2O3 is called iron (III) oxide because Fe+3 is present:
Fe O-2 → Fe2O3

15. Some More Examples Ca+2 + O-2 → CaO calcium oxide
Mg+2 + N-3 → Mg3N2 magnesium nitride
Al+3 + O-2 → Al2O aluminum oxide
K+ + I- → KI potassium iodide
Ba F- → BaF barium fluoride
Fe Cl-2 → Fe2Cl3 iron (III) chloride
Ti+4 + O-2 → Ti2O titanium (IV) oxide

16. Polyatomic Ions
groups of non-metalic atoms which combine and act as one
they have a charge… + or –
they often involve oxygen
polyatomic… poly meaning “many” atoms
some common polyatomic ions are:
e.g. NO2- nitrite e.g. NO3- nitrate
e.g. SO3-2 sulfite e.g. SO4-2 sulfate
e.g. CO3-2 carbonate e.g. OH- hydroxide
polyatomic (non-metalic) ions can combine with metalic ions to form ionic compounds
e.g. Ca+2 + CO3-2 → CaCO3 calcium carbonate

17. Naming Polyatomic Ionic Compounds
notice that compounds with polyatomic ions normally end with “ite” or “ate” … different from the “ide” ending used for regular ions
e.g. Cu NO3-2 → CuNO3
copper (II) nitrate
e.g. H+ + SO4-2 → H2SO4
hydrogen sulfate (also called sulfuric acid)

18. Molecular Compounds molecule diatomic molecules
is a cluster of atoms joined together
is the smallest independent unit of a pure substance
bond is strong
diatomic molecules
molecules made of 2 atoms of the same element… bond is strong
e.g. O2, N2, H2

19. binary molecular compounds
made of two different elements
e.g. carbon dioxide CO2
molecular compounds may be made of more than 2 elements… and in fact can become quite complex
e.g. glucose C6H12O6
each compound consists of specific proportions of each element

20. molecular compounds form from NON-METALS
bonds are created by the SHARING of an electron between elements
e.g. CO2 H O
H2O H

21. Characteristics of Molecular Compounds
made of two or more non metals
bonds formed by sharing of electrons
bonds are strong but attraction is weak (will break apart when changing state)
solid, liquid or gas at room temperature
poor conductors of electricity (no metals/ions)

22. Naming Molecular Compounds
Prefix + 1st Element Name
AND THEN
Prefix + 2nd Element Name
(ending changed to “ide”)
e.g. carbon dioxide CO2
the prefix in the written name matches the number of atoms of that element indicated in the formula

23. a prefix written before the name of the element it refers to
Prefixes tell us how many atoms of the element are present in the compound
1 = mono* 3 = tri 5 = penta
2 = di 4 = tetra 6 = hexa
(* mono is used with 2nd elements, and implied if no prefix is present with 1st elements)
a prefix written before the name of the element it refers to
e.g. N2O - dinitrogen monoxide
N2O3 - dinitrogen trioxide
PF5 - phosphorus pentafluoride
CO - carbon monoxide
CCl4 - carbon tetrachloride

24. the chemical formula will show how many atoms of each element are present in the compound
e.g. NH3 has 1 atom of N and 3 atoms of H
when drawing a representation of the compound make the element with the larger atomic mass larger H H N H

25. Some Molecular Compounds Also Have Common Names especially those with H

26. Properties of Molecular and Ionic Compounds