Subscript
The smaller numbers or letters beside the element symbol that tell you the number of atoms in the chemical formula, or the state of matter (at room temperature)
Four states of a Compound
(g) - gas, (L) - liquid, (s) - solid, (aq) - aqueous (a solution in which the solvent is water)
Metals
Elements that exist as single compounds
lose electrons and form positive ions
are named by their metal name followed by the word “ion” eg) sodium ion, lithium ion
Non-Metals
Elements that can exist as atoms or molecules
gain electrons and form negative ions
are named by changing the ending of the non-metal to “ide” then followed by the word “ion” eg) oxide ion, chloride ion
Compounds
Molecules made up of two or more different elements bonded together
Chemical Formulas
The elements in a compound (the symbols) and the amount of atoms belonging to each element (which is shown in the subscript)
Ion
An atom or group of atoms that have become electrically charged
Ionic Compounds
Pure substances formed as a result of the attraction between positive and negative ions
Ionic Compounds Characteristics
Solid at room temp, defined crystal structure, conducts electricity when liquid or dissolved in water, high melting points
How ions are formed
When atoms either lose or gain of electrons
Ion charge
The ion charge of an element on the periodic table (can be found in the superscript). Some elements may have more than one charge
Ionic bonds
formed when a positive and negative ion(s) (charges) attract each other
Steps to name ionic bonds
Look at the formula and write the name of the metal ion down first.
Write the name of the non-metal ion next but remember to change the ending to “ide”.
If the negative ion is a polyatomic ion, just write the name down as you see it on the periodic table.
Sometimes you will have a metal ion that has more than one possible charge. In the name, you must write Roman Numerals (I, II, III, IV, V, VI, etc) to show which ion it is.
Polyatomic ion
Bonded set of two or more atoms considered to behave as a single unit
Writing formulas (ion)
Write down the (+) metal ion first with it’s charge.
Write down the (-) non-metal ion second with it’s charge.
Keep adding either metal ions or non-metal ions until the positive and negative charges balance…they must add up to zero
Count the number of ions of each element. Put the number as a subscript to the right of the ion symbol and remove the ion charge. Note: the number “1” is invisible
Molecular Compound
A compound formed when two or more non-metals join together. They are joint when electrons are shared (a covalent bond)
Molecular compound characteristics
can be solids, liquids or gases at room temperature
do NOT conduct electricity when liquid or dissolved in water
have low melting points
Naming Molecular Compounds
Look at the formula and write down the element name for the first atom.
eg) OCl 2 the first element is “oxygen”
If there is more than one atom of the first element, add the appropriate prefix.
eg) OCl 2 there is only one oxygen so you leave it as “oxygen”
Write the name of the second atom with “ide” ending. Include the prefix. (***second element always has a prefix)
eg) OCl 2 the second element is “chloride” and there is 2 of them so you write “dichloride” the name of OCl 2 is “oxygen dichloride”
1 atoms
mono-
2 atoms
di-
3 atoms
tri-
4 atoms
tetra-
5 atoms
penta
6 atoms
hexa
7 atoms
hepta
8 atoms
octa-
9 atoms
nona-
10 atoms
deca-
Writing formulas (molecular)
Turn the element names into symbols. eg) dinitrogen tetraoxide NO
Turn the prefixes into subscripts.
eg) dinitrogen tetraoxide N2O4
Element
A basic substance that cannot be simplified. All elements are found on the periodic table
Atom
The smallest amount of an element
Molecule
Something formed when 2 or more atoms join together chemically