Compounds
A binary compound contains atoms of:
different elements
In a polyatomic ion, the atoms are joined by
Covalent bonds
Atoms that lose electrons have:
positive oxidation numbers
The sum of the mass numbers of all atoms in a molecule is equal to the molecule's
Formula mass
Every element has its own
Chemical symbol
In a chemical formula, the element written first is:
Metallic element
A polyatomic ion with a positive charge is the
Ammonium ion
An oxidation number indicates the number of electrons an atom can
gain, lose or share
Valence electrons make up an atom's
outermost energy level
How many atoms does a molecule of aluminium oxide contain ? Al2O3
5 atoms 2 Aluminium and 3 oxygen
An example of a binary compound is:
FeCl2 O2 Cl H2
FeCl2
A group of atoms that acts as a single atom when combining with other atoms is called a :
Polyatomic ion
The oxidation number of an atom of gold (III) is
3+
A subscript indicates the number of
atoms of an element in a compound
What is the formula mass of a molecule of aluminium chloride is the mass number of aluminium is 27 and the mass number of chlorine is 35?
AlCl3
132
27 * 1 = 27
35 * 3 = 105
105 + 27 = 132
Most diatomic molecules are
gases
An example of a diatomic molecule is :
H20 O2 He or CO2
O2
Oxidation numbers in a compound must add up to
0 (zero)
Each type of atom in a molecule has its own
chemical symbol and mass number
How many atoms does a molecule of sodium chloride contain?
NaCl
2
one atom of Na
one atom of Cl
A chemical formula represents
a compound
How are binary and diatomic compounds alike? how are they different?
they both are elements joined together by chemical bonds
binary compounds contain atoms of two different elements
diatomic contain two atoms of the same element
The oxidation number of an element in a compound may be indicated in the name by a
Roman numeral
The formula mass of a molecule made up of only one atom is:
the same as the element's mass number
What is the oxidation number of aluminum in aluminum chloride?
AlCl3
(oxidation number of Cl is 1- )
3+