a substance that has volume (occupies space) and has a mass
all matter are made up of atoms which bond together to produce different substances
matter and energy are not the same thing
everything is either matter or energy
energy does not have any atoms
energy and matter can change either and vice versa

first element to be found is helium - in the world

atoms

atom : building block of matter
1802: first atomic theory of matter was presented by John Dalton. Dalton proposed that all matter is made up of tiny spherical particles, which are indivisible and indestructible
we now know it is INCORRECT and atoms are in fact made of smaller subatomic particles (protons, neutrons and electrons)

Pure substances VS Mixtures

mater can be split into two groups: pure substances and mixtures

Mixtures

Mixtures: consist of 2 or more types of particles that are not chemically combined together. Can be made elements, compoounds or both
- air: oxygen gas (O2), Carbon dioxide gas (CO2), Nitrogen gas (N2)
- Oil-water mixture
Mixtures can be seperated by physical means (e.g. filtration)

Pure Substances

Pure substances: A pure substance is a substance made up of only one type of particle throughout. this means its has fixed composition and consistent properties. This can either be one single element or one single compound, but every sample of this substance that you examine must contain exactly the same thing with fixed, definite set of properties
- pure element: copper metal (cu)
- Pure compound: carbon dioxide gas (CO2)
It cannot be seperated by physical means (e.g. filtration)

Elements

Elements: Made of just one type of atoms
It could be monatomic (i.e exist as individual atoms) or could also form molecules
molecules: 2 or more atoms that are held together by chemical bonds
elements cannot be seperated into simpler substance by physical or chemical means

Compound

Compound: different type of atoms could combine to form new substances
To determine whether a pure substance is an element or a compound, you must determine if the substance can be broken down into simpler substances

Element	Compound
One type of atom Monoatomic E.g. O, C, H can be di- or poly- atomic, so long as they are made up of the dame type of atoms E.g. H2, O2, N2 (both elements, molecules/compounds)	2 or more atoms chemically bonded (e.g: covalent, ionic bonding) These atoms can be of the same or different elements

Molecules: 2 or more atoms that are covalently bonded
MOLECULES MUST BE COVALENTLY BONDED
all molecules are compounds but not all compounds are molecules
compounds are ionically bonded

Atomic structure

an atom is made up of three types of sub-atomic particles:
- protons (positively charged)
- Neutrons (neutral)
- Electrons (negatively charged)
in chemistry, the word particle is a general term that refers to a small unit of matter
Depending on the context, “particle“ could mean an atom, a molecule, an ion, or something else.

Atomic strctures

protons and neutrons are relatively equal mass and are huge in comparisions to electrons. This is why the nucleus is so dense
proton and neutron contribute nearly all the mass of the atom

Particle	Symbol	Charge	size relative to a proton	mass (kg)
proton	p	+1	1	1.673×10^-27
nucleus	n	1	1	1.675×10^-27
Electron	e	-1	1/1800	9.109×10^-31

Protons and neutrons are relatively equally mass and are huge in comparison to electrons. this is why the nucleus is dense
Proton and neutron contribute nearly all the mass of the atom

The Rutherford Experiment

Rutherford’s model proposed the following
- most of the mass of an atom and all of the positive charge must be located in a tiny central region called the nucleus
- Most of the volume of an atom is empty space, occupied only by electrons
- The electrons move in a circular orbits around the nucleus
- The force of the attraction between the positive nucleus and the negative electrons is electrostatic.
Prior to Rutherford’s experiment, the atom was thought to be a spherical cloud filled with protons and electrons all over (think raising caked, or plum pudding)
In 1911, Rutherford’s experiment proved that the atom has a tiny but heavy nucleus and that the most of the volume of an atoms is an empty space occupied by electrons

Bohr model

In 1913 Niels Bohr developed a new model of the hydrogen atom that explained emission spectra. The Bohr model proposed the following
- electrons revolve around the nucleus in fixed, circular orbits
- the electron’s orbits correspond to specific energy levels in the atom
- Electrons can only occupy fixed energy levels and
scientists quickly extended Bohr’s model of the hydrogen atom to the other atom
they proprosed that electrons were grouped in tdiffernt energy levels, called electron shells
these electron shells are labelled with the number n = 1, 2, 4
The electron shells
the highest energy level found is n7
highest energy level is found farther away from the nucleus because of the electrostatic attraction force
the higher up you go the higher the electrostatic attraction therefore lower energy the closer you get to the nucleus
if 2 negatively charged electrons share an electron shell have anti clockwise spins so they never meet or never come in contact with one another
think 2 siblings circling each other

Different types of atoms

the type of atom that make up each element is determined by the number of protons (atomic number) in the nucleus
- atomic number: the number of protons in the nucleus of the atom
- mass number: the total number of protons + neutrons in the nucleus
- Atoms are electrically neutral: therefore number of electrons = number of protons
the number of neutrons is calculated by: atomic mass - atomic number (number of electrons/protons)
the atomic number is usually the smaller number and the atomic mass is usually larger and has a lot of decimals

Isotopes

all atoms that belong to the same element have the same number of protons in the nucleus and therefore the same atomic number,
atoms that have the same number of protons (atomic number) but different numbers of neutrons (and therefore different mass ambers) are known as isotopes
isotopes have identical chemical properties but different physical properties such as mass and density. in particular, some isotopes are radioactive
In nature, different elements have different numbers of isotopes. Gold only has one isotope, whereas lead has four isotopes and mercury seven isotopes
Protons: determine elemental identity
Electrons: determine chemical reactivity(how easily (or not easily) it is for the atom to undergo change in a chemical reaction )
Neutrons: determine physical properties the physical properties of an element

Practice with Isotopes

Identify the most abundant form of carbon out of the 3

¹²₆ C - Carbon 12
¹³₆ C - Carbon 13
¹⁴₆ C - Carbon 14

Carbon 12 - it appears in the periodic table meaning it is the most commonly found Isotope
note that 12, 13, 14 are the atomic mass of the atom

Electron configuration

Using the bohr model it is possible to determine the basic electronic configuration of an atoms by applying the folowing rules

eaach shell can only contain a maximum number of electrons
lower enegy shells full before hugher ernergy shells

electron shell n	maximum number of electrons
1	2
2	8
3	18
4	32
n	2n²

Steps to annotating an atom - Electron configuration

determine the number of electrons in your element
recall the maximum number of electrons each shell can hold
place the number of electrons in the shells from the lowest energy to the highest energy. do no exceed the max number of electrons allowed
write the electronic configuration by listing the number of electrons in each shell separated by commas. (2, 8, 1) (for sodium)

THIS ONLY APPLIES TO THE FIRST 18 ELEMENTS (TILL ARGON)

Atoms

Atoms: Building block of matter

Ions

A positively or negatively charged atom or group of atom
remember than an atom has the same number of electrons and protons which means that is it neutral
When atoms pick up an additional electron (s) or lose electrons (s), there is no longer a balance between the positive and negative charge
They lose electrons/protons to achieve a full valence shell (octet rule)
- an exception to the octet rule would be the duet rule (applies to hydrogen & helium)
- the duet rules states that there would 2 electrons in the valence shell

2 main types of ions

monoatomic e.g.
a. Na⁺, Cl^-, Cu⁺²

Polyatomic
a. e.g. Pos₄^3-, OH^-

Cations

a positively charged ion (atom loses electrons)
- Meg2+, Al3+
Magnesium for example has 2,8,2
it loses 2 electrons and becomes
- Mg ^+2/2+
- You would also put square brackets around the visual representation and put a 2+/+2 in the upper right corner

Anions

Negatively chaged ion (atom gains electrons)
- e.g. Cl-, O2-
Chlorine for example has 2, 8, 7
It gains an electrons and becomes
- Cl^-
- there is an implied one

Metals

Metals have loosely held outershells (valence electrons)
they can lose these electrons to become cations, this is because the resulting ion has fewe electrons than protons

Nonmetals

non metals are attract electrons

Transition metals

they can take on more than 1 charge
they have variable charges
Really big valence shells so they can lose or gain electrons really easily

positive control : variable with known result (e.g. plant is exposed to sunlight)

negative control: absence of IV (e.g. plant exposed to no light)

No result (e.g. no change in plant height/mass)

Electron Transfer and Ionic Bonding

Recall classifying matter

atom : smallest particle of matter

Element: a substance made from only type of atom

Compound: A substance made from 2 or more different types of atoms

Molecules: A substance made from two or more atoms that chemically combined

Ionic compound

An ionic compound typically froms when a metal reacts with a nonmetal
Ionic compound = metallic cation + non metalli anion
During a reaction there is a transfer of electrons Metals → Non-metal
Once this occurs, the oppositely charged ions join together in a lattice
oppositely charged ions are attracted to one another and this attraction would be called an “electrostatic attraction”
electrostatic attraction AKA ionic bonds AKA the attraction between oppositely charged ions

Model	Example	does not show
chemical formula	NaCl	Charges Lattice structure
Dot and cross diagram		Lattice structure Ionic bonds
2D diagram		How ions were formed More than one layer
3D diagrams		Charges That there are no spaces between ions

They are brittle as when a force is applied to the lattice the ions with like charges align and actively repel each other shattering the lattice
The ionic bond is very strong, and brittle because rearranging ions causes repulsion between like charges
You are sliding the layers so the bond is still intact but the layers slide and the negatives end up next to negatives so they repel each other and then the lattice breaks apart
they normally have very high mpts
energy must be transferred to a substance to make it melt or boil
this energy overcome the strong electrostatic forces of attraction which act tin all directions between the oppositely charged ions
- Some forces are overcome during melting
- all remaining forces are overcome during boiling

the more energy needed the higher the melting point of boiling points
since the electrostatic forces of attraction between oppositely charged ions are strong, their melting and boiling points are high
solid sodium chloride needs a temperature of 801 degrees to melt it

Electron transfer diagrams

Electron transfer diagrams are used to show the path that electrons take when they are removed from a metal and added to a non-metal during ionic bonding
show the transfer of electrons from metals to non-metals

Steps to draw an electron transfer diagram

Draw an electron shell diagram of the neutral metal and non-metal
Add a ‘+‘ between them
Draw an arrow leading from each valence in the metal to the valence shell of the non-metal
Add an arrow towards the resulting ions
Draw an electron shell diagram of the resulting cation/s and anion/s
Write the chemical symbol of the metal and the non-metal in the centre of the electron shell diagram, taking care of the electron shell diagram, taking care to add charges to your ions.

Naming Ionic Compounds - rules

Name cations first (metals) before anions
If metal is a transition metal, indicate the valency in numerals after the name
- e.g: Fe (lll), Ag (l), Gold (l)
the name of the metal cation remains as is
- e.g: Sodium ion, Na⁺ ion
the name of the non-metal anion is changed. it’s suffix becomes ‘-ide‘

Shortcut method - e.g.

Al³⁺ + O^2-

Al₂ O₃