Compounds Flashcards
According to what are there rules for writing chemical formulae?
International Union of Pure and Applied Chemistry (IUPAC)
Why do compounds need names and formula?
- Can be overdosed
2. Clarity of which elements are present
Define chemical formula
Symbolic representation of a compound
What information does formulas give us?
- Name of compound
- Elements present
- Ratio of elements combined
Why should we understand how elements combine?
How they form compounds and how they affect things
When writing chemical formulae what do we use?
Valency - positive + negative
What do all halogens end with?
‘ide’
What do we use when writing formulae for non-transition metals?
Valency
When writing symbols of the elements for formulae. What goes first?
Metal goes first
What happens when there are two non-metals? formulae
Put the element furtherest to the left first (groups)
What happens when valency are the same?
They cancel = simplify
When writing formulae do the integer signs matter?
No. Used to indicate if receiving or giving ions. Formulae is positive
If a subscript is 1, what should happen?
Leave the 1 out
Define compounds
Consists of two or more different elements chemically bonded together in a fixed proportion
Which elements have more than one valency?
Transition metals
What is the formulae for transition metals written in?
Roman numerals
What happens when there is not stock notation?
Elements will have the valency of two
Why is silver an exception?
If no stock notation the valency will be one
I
1
II
2
III
3
IV
4 - iv drip
V
5 - vyf
VI
6
VII
7 - longer than six
How do you identify if a numeral is positive or negative?
Look at the other elements
What is the rule with integers?
There is always a positive and negative
What is an ionic compound?
Metal + non-metal
What is sign integer is a metal?
Positive
What is sign integer is a non-metal?
Negative
How do you write the chemical name for an ionic compound?
The metal is written first and retains its name. The nonmetal is after and changes as you add ‘ide’
What happens if the first element is a transition metal in and ionic bond when naming it?
Include the stock notation
What is a molecule compound?
Non-metal + non-metal
What happens to the second element in a molecule?
Ends in ‘ide’
What do you add to both element in a molecules?
Add pre-fixes to both elements
Why do we add a prefixes to the molecules?
Specifies the number of atoms present
Prefix 1
mono
Prefix 2
di
Prefix 3
tri
Prefix 4
tetra
Prefix 5
penta
Prefix 6
hexa
Prefix 7
hept
What is the exception for the prefix mono?
Is left out from the first element
What are polyatomic ions?
A common group of atoms that exist and behave as single units
What do the atoms have to do with the ion?
An ion is made up of multiple atoms tightly bonded together
Ammonium
NH4+
Valency of Ammonium
+1
Hydroxide
OH-
Valency of Hydroxide
-1
Nitrate
NO3-
Valency of Nitrate
-1
Sulphate
SO42-
Valency of Sulphate
-2
Carbonate
CO32-
Valency of Carbonate
-2
Phosphate
PO43-
Valency of Phosphate
-3
What does the name of the polyatomic ion mean?
The name stays the same, meaning no ‘ide’
When do we bracket the polyatomic ion?
Add bracket if you cannot simplify
