Chemistry Grade 9

Matter

anything that takes up space and has mass and volume

Property

is a characteristic or quality used to describe matter

QUALITATIVE Properties

properties that can be observed using the five senses (expessed in words)

QUANTITATIVE Properties

properties that involve a measurement

Physical Properties

properties that do not involve the formation of a new substance
can be qualitative or quantitative

Characteristic Physical Property

are properties that tend to be unique
can be used to identify matter

Chemical Properties

do involve the formation of a new substance

Hardness

a measure of how easily a mineral can be scratched

State

solid liquid or gas

Melleability

the ability to be made into different shapes (only SOLIDS)

Ductility

the malleability of something that can be drawing into wires or hammered into thin sheets

Melting and Boiling Points

The temperature at which substances change state.

Solubility

the quantity of a particular substance that can dissolve in a particular solvent (yielding a saturated solution)

Viscosity

the resistance of a gas or liquid to flow

Density

mass per unit volume

Clairity

the ability of light to travel through an object
*ONLY transparent(clear), Translucent (somewhat legible) and opaque (can see through)

Solute

the dissolved substance in a solution

Solvent

a liquid substance capable of dissolving other substances

Homogeneous Mixture

a mixture in which substances are evenly distributed throughout the mixture

Hetrogeneous Mixture

A mixture in which pure substances are unevenly distributed throughout the mixture

Electrical conductivity

how well a substance allows electricity to flow through it.

pure substance

Matter that always has exactly the same composition

mechanical mixture

a mixture whose components can be separated by mechanical means

Physical Changes

the particles in a substance DO NOT change
particles rearrange themselves and either spread out or move closer together

CHemical Change

the original substance is changed into a NEW substance that was not there

Volume

base x width x height

one centimetre =

one milliliter

milli --> base unit --> kilo

divide by 1000

milli <-- base unit <-- kilo

multiply by 1000

Density equals

mass
-------
volume

mass equals

volume x density

volume equals

mass
-------
density

Describe how water displacement can be used to find the volume of an irregularly shaped object

water displacement can used to find the volume of an object by using an overflow can that filled to the top and placing the object gently in the can. the excess water will go out the spout and into a graduated cylinder where the cylinder will measure the

Physical properties of metals are

luster, good conductors of heat and electricity, high density, high melting point, ductile and malleable

Chemical Properties of Metals are

easily lose electrons, corrode easily

Physical properties of non metals are

no luster, not malleable, low density, low melting point, poor conductor of heat and electricity, brittle and not ductile

Chemical properties of non metals are

tend to gain electrons

Physical properties of Metalloid's are

solids, shiny OR dull, ductile, malleable and are able to conduct heat and electrons well but not as well as metals

Periodic table of elements

metals are the 88 elements to the left of the staircase line
non metals are to the right of the staircase line
metalloid's are on both sides of the staircase line

Group one

alkali metals: highly reactive,

Group two

alkaline metals: not as reactive as alkali metals

Group seven

halogens: very reactive

Group eight

noble gases: not reactive

Periods are:

the horizontal row on the periodic table

Dmitri Mendeleev created what?

the periodic table
he organized the table by grouping elements with similar characteristics

Elements in the same period fill up

the same energy level as move left to right

Vertical Columns are called

groups or families

Valence electrons are

the electrons in the outermost shell of the atom

the ______ ____ have full outer shells which make the inert

noble gases

Hydrogen is

the only orphan because it behaves like no other element

Democritus (400 BCE)

theorized:
atoms are of different sizes, are in constent motion and are separated by empty spaces

Aristotle (450 BCE)

theorized:
all matter is made up of four basic elements: earth, air water and fire

John Dalton (1807)

theorized:
matter is made up of tiny invisible particles, atoms of the same element are identical, atoms of different elements are different, atoms are arranged to form new substances in chemical reactions

J.J Thompson (1897)

theorized:
atoms contain negatively charged electrons
since atoms are neutral the rest of the atom is a positively charged sphere while there are negatively charged atoms distributed throughout the atom

Ernest Rutherford (1909)

theorized:
the center of an atom is positively charged and the center is called the nucleus which contains almost all the atoms mass but occupies a small amount of space, the nucleus is surrounded by a cloud of negatively charged electrons, most of the at

James Chadwick (1932)

theorized:
an atom must be a empty sphere with a dense central nucleus, the nucleus contains positively charged protons, the mas of a neutron is about the same as a proton, the neutral atom has the same number of protons as electrons

Neils Bohr (1913)

theorized:
electrons orbit the nucleus of the atom much like the planets orbit the sun, each electron in an orbit has a definite amount of energy, the further the electron from the nucleus the greater the energy

Atomic Number

the number of protons in the atom
NO TWO ATOMS HAVE THE SAME ATOMIC NUMBER

Mass Number

the number of protons and neutrons inside the nucleus

Drawing Atoms

1. + and neutrons form the nucleus at the center of the atom
2. electrons are in shells around the nucleus
3. 1st shell hold 2 - 2nd 8 - and 3rd 8 -

Isotopes

atoms of the same element that have different numbers of neutrons

Isotopes

all have the same amount of protons and electrons

the symbol of an element

represent one atom of that element

if there are more than one atom in the element then

a subscript number is used to indicate how many there are

if there is a subscript outside a bracket...

then you multiply all the elements inside the brackets

a coefficient number (a number that goes before a chemical symbol) is written before the chemical symbol

then it indicates the number of atoms of that element
eg. 3 C = three carbon atoms

a coefficient number (a number that goes before a chemical formula) is written before the chemical formula

indicates the number of molecules of that compound

when counting atoms always

Multiply

Chemical bonding occurs when

atoms try to fill their outer shell to make themselves stable

atoms get a full outer shell by

1.gaining or losing electrons making IONIC bonding
2. will share electrons making COVALENT bonding

Group 1 to 3 elements

lose enough electrons to get to 0 valence electrons

Group 4 elements

gain or lose 4 electrons

group 5 through 8 elements

gain enough electrons to add to 8 valence electrons

Atoms can be

chemically combined to other atoms to form small units called molecules

Molecular Compounds

are molecules consisting of atoms from different elements
(both of these types of bonding occurs between two or more non metals and electrons are shared by the 2 atoms) oftentimes called covalent bonding

Molecular Elements

are molecules consisting of the same element

Ionic Compounds

this type of bonding occurs between metal and non metal made from ions losing or gaining electrons

You test for gases when

you cant tell the difference between the two substance using physical properties or chemical changes

Glowing Splint test - Oxygen

if you suspect a clear colorless gas
light a wooden splint and blow out the flame hold it near the unknown gas and if it bursts into flames its oxygen

The Burling Splint Test - Hydrogen

light a wooden splint and hold it near the unknown gas if you hear a popping sound the gas is Hydrogen

the Limewater Test - Carbon dioxide

bubble the unknown gas through a lime water solution and if the water turns milky the gas is carbon dioxide