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SCIENCE 9
UNIT 2
MATTER AND CHEMICAL CHANGE
TOPIC 1 EXPLORING MATTER
CHEMISTRY- the study of the properties of matter and the changes matter undergoes.
CAUSTIC- a material that burns, corrodes, or destroys organic tissue
THE PARTICLE MODEL OF MATTER
- All matter is made up of extremely tiny particles
- Each pure substance has its own kind of particle, different from the particles of
other pure substances
- Particles attract each other
- Particles are always moving
- Particles at a higher temperature move faster on average than particles at a lower
temperature
HOMOGENEOUS MIXTURE- a mixture in which particles are uniformly scattered; has
a uniform composition
HETEROGENEOUS MIXTURE- a mixture in which the particles are not uniformly
scattered; does not have a uniform composition
TOPIC 2 CHANGES IN MATTER
PHYSICAL CHANGE- change in form but not in chemical composition; no new
substances are formed
CHEMICAL CHANGE- a change in which one or more new chemical substances are
formed
TOPIC 3 WHAT ARE ELEMENTS?
THE LAW OF CONSERVATION OF MASS- in a chemical change, the total mass of
the new substances is always the same as the total mass of the original substances
THE LAW OF DEFINITE COMPOSITON- compounds are pure substances that contain
two or more elements combined together in fixed (or definite) proportions
ELECTROLYSIS- the process of decomposing a chemical compound by passing an
electric current through it
ELEMENT- is a pure substance made up of one type of particle, or atom. Eache element
has its own distinct properties and cannot be broken down into simpler substances by
means of a chemical change.
COMPOUNDS- are pure substances that are made up of two or more elements
chemically combined together. Compounds can be broken down into elements again by
chemical means
DALTON’S ATOMIC THEORY
- All matter is made up of small particles called atoms
- Atoms cannot be created, destroyed, or divided into smaller particles
- All atoms of the same element are identical in mass and size. Atoms of one
element are different in mass and size from the atoms of other elements
- Compounds are created when atoms of different elements link together in definite
proportions
ELECTRONS- negatively charged particles
ATOMIC NUCLEUS- the centre of the atom; contains the protons and neutrons
PROTON- positively charged particle found inside the atomic nucleus
NEUTRONS- uncharged particles in the atomic nucleus
TOPIC 4 CLASSIFYING ELEMENTS
ELEMENT SYMBOLS- one or more letters used to represent the name of a substance
(e.g., O is the symbol for oxygen)
CHEMICAL FAMILY- a group of related elements that have similar properties
TOPIC 5 THE PERIODIC TABLE
ATOMIC MASS- the average mass of an atom of an element
ATOMIC NUMBER- the number of protons in the nucleus of an atom
TOPIC 6 CHEMICAL COMPOUNDS
IONIC COMPOUND- formed when atoms transfer electrons to or from other atoms
MOLECULAR COMPOUND- formed when atoms share electrons
CHEMICAL FORMULA- a formula that shows the number and types of atoms in a
molecule
MOLECULE- smallest indepe3ndent unit of a pure substance, generally a cluster of
atoms joined together
DIATOMIC MOLECULES- molecules made of two atoms of the same element
BINARY COMPOUND- compounds made of two elements
ION- a particle or group of particles with a positive or negative charge
CONDUCTIVITY- the ability of a substance to carry and electrical current
TOPIC 7 CHEMICAL REACTIONS
CHEMICAL REACTION- a process in which a substance is changed into one or more
new substances
REACTANTS- the substances that go into a chemical reaction
PRODUCTS- the substances produced by a chemical reaction
EXOTHERMIC REACTION- a chemical reaction in which heat energy is released to the
surroundings
ENDOTHERMIC REACTION- a chemical reaction in which heat energy is taken in
from the surroundings
TOPIC 8 REACTION RATE
REACTION RATE- the measure of how fast a reaction occurs
CATALYST- a substance that speeds up a chemical reaction without being used up in a
reaction
ENZYME- a special protein molecule that regulates chemical reactions in living
organisms
INHIBITORS- substances that slow down or prevent chemical reactions
CORROSION- a process whereby metals or stone are chemically degraded or broken
down
RUST- iron oxide, a product of the chemical reaction of iron, oxygen, and moisture
GALVANIZATION- the process of protecting metals by coating them with a thin layer
of zinc
COMBUSTION- the highly exothermic combination of a substance with oxygen;
requires heat, oxygen and fuel