GRADE 9 REVIEW Lesson 1 Flashcards
A pure substance is…
A substance that is made up of only one particle. Example: Iron (FE), Water (H2O)
A mixture is…
A substance that is made up of at least two different types of particles. Example: Seawater (Salt + water)
A mechanical mixture/heterogeneous mixture is…
a mixture in which you can distinguish different types of matter. Example: Trail mix, Chex mix
A solution/homogeneous mixture is…
a uniform mixture of 2 or more substances (alloys).
Examples: 18K Gold (gold + copper), Apple juice (sugar + fruit extract + water), gas mixture (iodine gas + air)
An element is…
a substance that can not be broken down by chemical or physical means.
Examples: Sodium (Na), Bromine (BR2), Oxygen (O2)
A compound is…
2 or more elements that are chemically joined
Examples: Table salt (NaCI), Ethanol (C2H5OH), Carbon dioxide (CO2)
An atom is…
the smallest unit of matter that cannot be broken down chemically. It is made up of nucleas, protons, and neutrons.
A molecule is…
a group of two or more atoms held together by attractive forces known as chemical bonds
Particle Theory (5)!
- All matter is made up of tiny particles known as atoms.
- Particles are constantly in motion.
- Particles attract each other.
- Particles have spaces between them.
- As temperature increases, particles move faster.
Physical Change and Clues of it
Substance may change state or its form, but it still remains the same substance. No new substances have been formed.
Clues:
1. Change of state
2. Changes form (i.e. smaller pieces)
Chemical Change and Clues of it
the original substance is changed into a different substance that has different properties
- often irreversible
Clues:
1. colour change
2. energy release (thermal or light energy)
3. starting materials (reactants) disappear
4. gas is produced
5. precipitate is formed (a solid is formed from two liquids)
NOTE: these clues indicate that a chemical change has probably taken place.
