chemistry - grade 9

particle theory of matter

1. all matter is made up of particles
2. all particles have a little space between them
3. all particles in a substance are identical
4. all particles are in constant motion
5. all particles in the same substance are attracted to each other

4 factors that effect the state of matter

1. energy
2. speed
3. distance
4. attraction

chemistry

the study of matter and the changes it undergoes

pure substance

1 type of particle combined by chemical means

diatomic element

2 of the same atom

what are the diatomic elements?

H, O, F, Br, I, N, Cl

simple element

1 atom

compound

2 or more different atoms that are chemically combined

molecule

a compound/substance with only 1 type of atom

mixture

2 or more particles combined by physical means

homogenous

1 visible phase

solution

when a solute is dissolved in a solvent

alloy

metals melted together

heterogenous

2 visible phases

mechanical mixture

all parts are visible and can be separated

suspension mixture

particles suspended in a gas or liquid

chemical property

characteristic of a substance that happens during a reaction

physical property

described or measurable characteristic of matter

qualitative properties

luster, clarity, brittleness, ductility, viscosity, hardness, malleability

quantitative properties

density, boiling point, freezing point, melting point

density formulae

D=M/V

V=M/D

M=V x D

what is an element?

a name for a type of atom

what do elements contain?

protons (+) electrons (-) neutrons (neutral)

metals

ductile, malleble, lusterous, conductive

non-metals

not conductive

metalloids

found on the staircase and have properties of both metals and non-metals

atomic number

number of protons

atomic mass

mass of protons + neutrons

read this standard atomic notation

atomic mass: 9 amu

atomic number: 4

read this standard atomic notation

atomic mass: 23 amu

atomic number: 11

isotopes

• type of element
• same number of proton
• different number of neutrons/mass

carbon dating

looking at the ratio of C-12 to C-14 in a substance to see how many thousands of years an organism has been dead

where does C-14 come from?

Nitrogen. It also takes 5,730 for half of it to turn back into Nitrogen

period number tells us what?

the number of orbitals

group number tells us what?

the number of valence electrons

group 1

• alkali metals
• lustrous, silvery, soft, highly reactive

group 2

• alkaline earth metals
• burn bright colorful flames
• lustrous, silvery
• not as soft of reactive as group 1

group 3-12

• transition metals
• different states of matter
• conductive
• high melting and boiling points

group 17

• halogens
• highly reactive
• different states of matter
• poisonous in large amounts

group 18

• noble gases
• colorless, odorless, tasteless
• stable
• glow brightly when electricity passes through

why is hydrogen on the metal side if its not a metal?

it shares similar properties like 1 valence electron and reactivity

Democritus

came up with the idea of small indivible particles called atoms

Aristotle

rejected the idea of atoms, thought everything is elemental

Dalton

billiard ball model, all atoms of a specific are the same

Thomson

chocolate chip cookie model, electrons being evenly disturbed inside positive space

Rutherford

discovered protons + nucleus, predicted the discovery of neutrons. Together these subatomic particles make up the mass of atoms. Also stated that electrons surrounded the nucleus in a cloud

Bohr

said electrons orbit nucleus in shells like planets (bohr-rutherford planetary model)

Chadwick

discovered neutral subatomic particles called neutrons. Said that neutrons and protons make up the mass of atoms

law

a universally accepted fact, the foundation of science

hypothesis

an educated guess, can be disproven or proven with just one experiment

theory

explanation for a set of observations, based upon verified hypothesis. NOT a fact

physical change

change in state/arraignment, no new substance formed (ex: freezing)

chemical change

2 substances react to form new subsance

5 evidence of chemical change

• new color
• new odor
• precipitate (solid made from 2 liquids)
• hard to reverse
• gas formation

ion

charged atom

cation

looses electrons to become a positively charged atom. Looses electrons if it has less than 4 electrons

anion

gains electrons to become a negatively charged atom. gains electrons if it has more than 4 electrons

count this atom

5 molecules

10 Al

15 S

60 0

count this atom:

Na2SO4

2 Na

1 S

4 O