chemical formula d. crowley, 2007. chemical formula to understand chemical formula
TRANSCRIPT
CHEMICAL FORMULA
D. Crowley, 2007
Chemical Formula
To understand chemical formula
Definitions
Define an element, compound and mixture
An element is made up of just one type of atom
A compound is two or more elements, chemically bound
A mixture is made of different substances, not chemically bound
Elements & Compounds
Look at the rocket - it uses liquid hydrogen as a fuel The engine mixes this hydrogen with oxygen, adds a
spark and the reaction takes place
The elements are
They react together, forming a compound called
Elements & Compounds
Look at the rocket - it uses liquid hydrogen as a fuel The engine mixes this hydrogen with oxygen, adds a
spark and the reaction takes place
The elements are hydrogen and oxygen
They react together, forming a compound calledhydrogen oxide (water)!
Chemical Equations
Chemical equations show us our reactants and products
reactants products
They can be word or symbol equations, e.g.
Carbon + oxygen carbon monoxide
C + O CO
Formula
Elements and compounds can be represented using chemical formula We use numbers in the formula, which represents the number of
atoms present (as a ratio)
C = 1 atom of carbon (C)
O2 = 2 atoms of oxygen (O)
CO2 = 1 atom of carbon (C); 2 atoms of oxygen (O)
NaCl = 1 atom of sodium (Na); 1 atom of chlorine (Cl)
H2SO4 = 2 atoms of hydrogen (H); 1 atom of sulphur (S); 4 atoms of oxygen (O)
Graphical
Can you draw the following substances The formula should help you graphically represent them…
Carbon dioxideCO2
Sodium chlorideNaCl
Sulphuric acidH2SO4
OxygenO2
CarbonC
Nitric acidHNO3
Graphical
Can you draw the following substances The formula should help you graphically represent them…
Carbon dioxideCO2
Sodium chlorideNaCl
Sulphuric acidH2SO4
OxygenO2
CarbonC
Nitric acidHNO3
Graphical
Can you draw the following substances The formula should help you graphically represent them…
Carbon dioxideCO2
Sodium chlorideNaCl
Sulphuric acidH2SO4
OxygenO2
CarbonC
Nitric acidHNO3
Graphical
Can you draw the following substances The formula should help you graphically represent them…
Carbon dioxideCO2
Sulphuric acidH2SO4
OxygenO2
CarbonC
Sodium chlorideNaCl
Nitric acidHNO3
Graphical
Can you draw the following substances The formula should help you graphically represent them…
Carbon dioxideCO2
Sulphuric acidH2SO4
OxygenO2
CarbonC
Sodium chlorideNaCl
Nitric acidHNO3
Graphical
Can you draw the following substances The formula should help you graphically represent them…
Carbon dioxideCO2
Sulphuric acidH2SO4
OxygenO2
CarbonC
Sodium chlorideNaCl
Nitric acidHNO3
Questions
Write down how many atoms there are (and of what element) for the following: -
1) C - e.g. 1 x carbon (C) 2) CO2
3) H2O
4) CaCO3
5) H2SO4
6) NaCl7) HNO3
8) CuCO3
9) MgCl210) Carbon monoxide11) Hydrogen oxide
Presentation
If there is time left, produce a poster in your book which explains formula (as a revision guide)
You may wish to add examples, and ways to work out the ratio of atoms…