Chapter 06 - Chemical Formulae and Equations Flashcards
What do chemical formulae tell us?
The ratio of elements combined in one unit of substance, they contain chemical symbols (indicates the element) and subscript (indicates the number of atoms present in each element)
What are the 3 types that elements can exist as?
1) Monoatomic elements
2) Diatomic elements
3) Polyatomic elements
What are monoatomic elements?
Monoatomic elements have uncombined atoms with fully filled valence electron shells that exist independently (e.g. noble gases)
What are diatomic molecules?
Molecules that have 2 chemically combined atoms (e.g. H2, I2)
What are polyatomic molecules?
Molecules that have 3 or more chemically combined atoms (e.g. Sulfur, Phosphorus)
What are the 5 main polyatomic ions?
1) Ammonium ions
2) Hydroxide ions
3) Nitrate ions
4) Carbonate ions
5) Sulfate ions
What is the chemical symbol for ammonium ions?
NH4+
What is the chemical symbol for hydroxide ions?
OH-
What is the chemical symbol for nitrate ions?
NO3-
What is the chemical symbol for carbonate ions?
CO3 ^2-
What is the chemical symbol for sulfate ions?
SO4 ^2-
What are the good to know ions?
1) Hydrogen carbonate ions
2) Ethanoate ions
3) Manganate (III) ions
4) Dichromate (VI) ions
5) Phosphate ions
What is the chemical symbol for hydrogen carbonate ions?
HCO3-
What is the chemical symbol for ethanoate ions?
CH3COO-
What is the chemical symbol for manganate (III) ions?
MnO4-
What is the chemical symbol for dichromate (VI) ions?
Cr2O7 ^2-
What is the chemical symbol for phosphate ions?
PO4 ^3-
How do you identify the valency of an element?
By looking at its group number in the periodic table (e.g.
Group 1 = Valency 1
Group 13 = Valency 3
Group 15 = Valency 3)
As transition metallic elements have variable valencies, their valencies are indicated by a ____ ____
Roman numeral (e.g.
Copper (II) = Valency 2
Lead (IV) = Valency 4
Manganese (VI) = Valency 6)
Chemical formulae that are fixed are ____ while chemical formulae that are not fixed are ____
compounds, mixtures
What are the 4 steps in writing chemical formulae?
1) Write the respective valency and criss-cross
2) If valencies are equal, just write out formula
3) If there are more than 1 polyatomic ion, use brackets
4) Reduce the ratio by a common factor if possible
What are the valencies for zinc and silver?
Zinc = 2 (Zn2+)
Silver = 1 (Ag+)
What are the 2 key points when naming an ionic compounds containing 2 elements
1) The metallic elements comes before the non metallic element
2) Non-metallic elements end with ‘ide’ (e.g. calcium + chlorine = calcium chloride)
Only one type ion will not change its name after combining with other elements. What ion is that?
Polyatomic ions (e.g. sodium carbonate, potassium sulfate)
What are the 3 key points when naming a covalent compound?
1) The first element name remain unchanged
2) The second element name ends with ‘ide’
3) A prefix is used for the second element depending on the number of atoms involved
(1 atom = mono
2 atoms = di
3 atom = tri
4 atoms = tetra)
Certain covalent compounds have special names (e.g. ammonia, water)
Atoms can neither be ____ nor ____
destroyed nor created
The sum of atoms before a reaction = the sum of atoms after a reaction
What are the 4 state symbols?
1) Solid (s)
2) Liquid (l)
3) Gas (g)
4) Aqueous (aq) - dissolved in water
Name 2 common solids
1) Most metals (Fe, Cu)
2) Ionic compounds (NaCl)
3) Sulfur (S)
4) Phosphorus (P)
5) Carbon (as graphite/diamond)
Name 2 common liquids
1) Water
2) Mercury
3) Bromine
Name 2 common gases
1) Oxygen
2) Nitrogen
3) Hydrogen
4) Chlorine
5) Fluorine
6) Noble gases
Name 2 common aqueous substances
1) Acids
2) Bases
3) Salts (when dissolved in water)
What are the 5 steps to writing chemical equations
1) Write the chemical formulae of products and reactants
2) List the number of atoms presents in each element
3) Add molecules to balance
4) Re count the number of atoms on each side and make sure they are the same
5) Write down the final equation
What are the 3 steps to converting word equations to chemical equations
1) Identify reactants and products and place them in a word equation
2) Convert the chemical names into chemical formulae
3) Balance the chemical equation
What are the 2 types of balanced ionic equations?
1) Solubility of substances in water
2) Change in oxidation states
What are the 3 steps to writing an ionic equation?
1) Identify the ionic compounds that are soluble (forming aq solutions) and will dissociate into ions in water (Insoluble substance can’t dissociate)
2) Cancel out spectator ions (ions that remain the same in their original states before and after a chemical reaction)
3) Write a balanced ionic equation with state symbols
