Chemistry Notes - Chapter 1
Matter - Anything that occupies space and has a mass
Mass - the quantity of matter in an object (mass is independent of location)
Weight- the result of mass acted upon by gravity (weight depends on location, depends on the
force of gravity at certain location)
Atoms:
The smallest unit of an element that has all of the properties of an element.
Elements:
- A substance that consists of identical atoms (118 known elements as of April 2011)
- their symbols consist of one or two letters
Monatomic:
- helium (He) and neon (Ne)
Diatomic:
- elements that consist of 2 atoms (diatomic)
- H2, N2 , O2, Cl2
Polyatomic:
- elements with many atoms
- O3 , P4, S8 ‘ Cn
Compound:
- A pure substance made up of two or more elements in a fixed ratio by mass
- (Ex.) NaCl: the ratio of sodium atoms to chlorine atoms in sodium chloride is 1:1
- C6H6 : there are 6 carbon atoms and 6 hydrogen atoms in this compound.
Mixtures:
- A combination of two or more pure substances.
- Homogeneous > Uniform composition
- Heterogeneous > Non-uniform composition
Chemical Change
- Involves a change in chemical composition.
- Results in a change in composition or structure
In a chemical reaction, substances are used up and others formed in their place.
Physical Change
- A change that does not entail any change in the chemical composition, Strictly just
physical changes.
- (Ex.) Ice cube melting or water evaporating
- The composition of the matter stays the same
Matter - Anything that occupies space and has a mass
Mass - the quantity of matter in an object (mass is independent of location)
Weight- the result of mass acted upon by gravity (weight depends on location, depends on the
force of gravity at certain location)
Atoms:
The smallest unit of an element that has all of the properties of an element.
Elements:
- A substance that consists of identical atoms (118 known elements as of April 2011)
- their symbols consist of one or two letters
Monatomic:
- helium (He) and neon (Ne)
Diatomic:
- elements that consist of 2 atoms (diatomic)
- H2, N2 , O2, Cl2
Polyatomic:
- elements with many atoms
- O3 , P4, S8 ‘ Cn
Compound:
- A pure substance made up of two or more elements in a fixed ratio by mass
- (Ex.) NaCl: the ratio of sodium atoms to chlorine atoms in sodium chloride is 1:1
- C6H6 : there are 6 carbon atoms and 6 hydrogen atoms in this compound.
Mixtures:
- A combination of two or more pure substances.
- Homogeneous > Uniform composition
- Heterogeneous > Non-uniform composition
Chemical Change
- Involves a change in chemical composition.
- Results in a change in composition or structure
In a chemical reaction, substances are used up and others formed in their place.
Physical Change
- A change that does not entail any change in the chemical composition, Strictly just
physical changes.
- (Ex.) Ice cube melting or water evaporating
- The composition of the matter stays the same
