grade 9 chemistry unit test

matter

anything that has mass and takes up space

how do states of matter differ

distance between particles, strength of attraction between particles, degrees of motion

solid

definite shape, defined volume, unable to flow, can be compressed very very slightly, very small volume change in heating

liquid

infinite shape, defined volume, can flow, can be compressed very slightly, very small volume change with heating

gas

infinite shape, undefined volume, can flow, can be compressed greatly, very large volume change with heating

particle theory

all matter is made up of particles

all particles of one substance are identical

spaces between particles are very large compared to the size of the particles themselves

the particles in matter attract each other - the cloer the particles are the stronger the force is

all the particles of matter are constantly moving - motion can increase or decrease due to changes in temperature

types of matter

pure substance and mixture

2 pure substances

element and compound

2 mixtures

homogenous and heterogenous

pure substance

matter than contains only one kind of particle

element

cannot me broken down into smaller parts, typically found on periodic table

compounds

substances that are made of 2 or more elements that are chemically connected, typically through chemical bonds

mixture

matter that contains more than one kind of particle and can be sperated

heterogenous mixture

mixtures where you can see the different parts

homogenous mixture

mixture where you can only see one phase, the different parts are all mixed together, one substance is usually dissolved in another

physical property

a characteristic or a description of a substance that can help identify it, properties can be easily measured or observed

qualitative properties

can observe with senses

quantitative properties

can be measured and have a numerical value

physical property 5 examples

color, texture, luster, clarity, form

chemical properties

when substances combine or react together, describe what happens to a substance as it becomes a new substance

chemical properties 5 examples

combustibility, reaction with acid, reaction with oxygen, toxicity, radioactivity

physical changes

change in form or state of a substance, no new substances are formed

3 main types of physical changes

changes of state - reversible, dissolving - reversible, breaking a substance - inreversible

chemical changes

the original substance is changed into one or more new substances, new substance has different properties

5 clues of chemical change

change in colour

new gas/odour is formed

new solid forms (precipitate)

difficult to reverse (not worth it)

heat or light is given off

early greek belief

earth was made of fire, earth, and water

democritus beliefs

stated that matter is composed of tiny particles called atoms, which means indivisible

john dalton’s atomic theory

all matter is made of atoms, atoms can join together to form larger particles called molecules, differnet elements have different properties, atoms of the same element are identical

what was dalton’s atomic theory unable to prove

electricity

jj thompston’s model of the atom

involved a cathode ray tube which is a vacuum tube that fires beams of particles through a tube, which are seen on a phosphorescent screen, led to discovery of electrons

jj thompson findings

atoms have positive and negative particles, an atom is made up of mostly positive particles with negative particles scattered throughout the positive ones

discovered the electron

ernest rutherford’s atomic model

fired beans of heavy positively charged particles (alpha particles) through gold foil and used fluorescent zinc-sulfide screens. noticed that 90% of the particles went right through the foil, therefore there must be mostly empty space between the atoms in the gold foil. some particles were deflected, therefore there is a small positive charge in the centre of atoms. few particles were greatly deflected, therefore atoms have a small, dense, and positively charged centre

niel bohr

discovered that electrons only exist in shells around the nucleus and that each shell is a certain distance from the nucleus and can only have a certain number of electrons

periods

rows going down periodic table

groups/families

columns of periodic table

what do periods tell us

how many orbitals each atom has

what to groups tell us

number of valence electrons an atoms has

properties of metals

shiny, good conductors of heat and electricity, usually solid, malleable, ductile

properties of non-metals

dull, bad conductors, brittle

metalloids

mains: Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te)

additional: Polonium (Po), Astatine (At), Selenium (Se)

have properties of both metals and non-metals

appear shiny and metallic and solid

are semiconductors and are brittle

alkali metals

lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr)

want to lose their single valence electron

low density, highly radioactive, low melting points

very soft, high conductivity

alkaline earth metals

beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra)

not as reactive as alkali metals but are still reactive

silvery-white metallic elements

good conductors

found naturally in earths crust and form alkaline solutions when mixed with water

transition metals

good conductors of heat and electricity, brightly coloured

halogens

fluorine (F), chlorine (Cl), bromine (Br), Iodine (I), astatine (At), tennessine (Ts)

1 electron short from full outer shell - very reactive

high electrinegativity, forms salts

poor conductors

highly toxic and corrosive in pure forms

noble gases

helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), oganesson (Og)

very stable, conduct electricity well, glow in bright colours

full outer shell

aka inert gas or rare gas

electron

negative, in orbitals

proton

positive, in nucleus

neutron

neutral, in nucleus

octet rule

atoms need a full valence shell of 8 electrons, which means they need to either gain or lose electrons

cation

metals that lose electrons and become positively charged

anion

non-metals gain electrons and become negatively charged

naming ions

cation - stay the same

anion - add ‘ide’ to the end of the name

ionic compounds

made up of a metal and a non-metal, non-metal gains electrons from the metal

ionic bond

the attraction that holds the oppositely charged ions together

properties of ionic compounds

hard, brittle, cannot be stretched, high melting and boiling points, conduct electricity, easily cracked

formulas for ionic compounds

crossover method - ion charges become subscripts for the opposite element and you drop the charge

naming ionic compounds

name the metal first then name the non-metal and change the ending to ‘ide’

ionic bonding

between ions, between a non-metal and a metal. electrons from the cation go to the anion

what 2 subatomic particles contribute to the mass of an atom

protons, neutrons

isotopes

atoms of the same element that have a different number of neutrons

atomic mass

the weighted average of the masses of all the isotopes for that element

colvalent compounds

formed between 2 non-metals, who share valence electrons and form molecules

diatomic molecules

special group of molecules made up of 2 atoms, can share 1 2 or 3 pairs of electrons

what 7 elements occur naturally as diatomic molecules

hydrogen, oxygen, fluorine, bromine, iodine, chlorine, nitrogen

what 2 subatomic particles contribute to the mass of an atom

proton and neutron