Fundamental Chemistry

Elements with different ion charges

Iron → Fe²⁺, Fe³⁺

Copper → Cu⁺, Cu²⁺

Cobalt → Co²⁺, Co³⁺

Chromium → Cr²⁺, Cr³⁺, Cr⁶⁺

Hydrogen

H (atomic number 1)

Helium

He (atomic number 2)

Lithium

Li (atomic number 3)

Beryllium

Be (atomic number 4)

Boron

B (atomic number 5)

Carbon

C (atomic number 6)

Nitrogen

N (atomic number 7)

Oxygen

O (atomic number 8)

Fluorine

F (atomic number 9)

Neon

Ne (atomic number 10)

Sodium

Na (atomic number 11)

Magnesium

Mg (atomic number 12)

Aluminum

Al (atomic number 13)

Silicon

Si (atomic number 14)

Phosphorus

P (atomic number 15)

Sulfur

S (atomic number 16)

Chlorine

Cl (atomic number 17)

Argon

Ar (atomic number 18)

Potassium

K (atomic number 19)

Calcium

Ca (atomic number 20)

Scandium

Sc (atomic number 21)

Titanium

Ti (atomic number 22)

Vanadium

V (atomic number 23)

Chromium

Cr (atomic number 24)

Manganese Mn (atomic number 25)

Iron

Fe (atomic number 26)

Cobalt

Co (atomic number 27)

Nickel

Ni (atomic number 28)

Copper

Cu (atomic number 29)

Zinc

Zn (atomic number 30)

Acetate

C₂H₃O₂⁻

Nitrite

NO₂⁻

Carbonate

CO₃²⁻

Sulfate

SO₄²⁻

Phosphate

PO₄³⁻

Permanganate

MnO₄⁻

Hypochlorite

ClO⁻

Dichromate

Cr₂O₇²⁻

Hydrogen carbonate (bicarbonate)

HCO₃⁻

Formate

HCO₂⁻

Sulfite

SO₃²⁻

Nitrate

NO₃⁻

Peroxide

O₂²⁻

Hydrogen sulfate (Bisulfate)

HSO₄⁻

Perchlorate

ClO₄⁻

Ammonium

NH₄⁺

Cyanide

CN⁻

Hydroxide

OH⁻

What is matter

anything that has mass and occupies space

what are the 2 main types of matter

pure substances and mixtures

what is a pure substance

a matter with a fixed (constant) composition and definite properties. elements and compounds

what is an element

a substance made of only one type of atom

what is a compound

a substance made of two or more different types of atoms, chemically bonded in a fixed ratio

what is a mixture

matter with variable composition made by physically combining substances

what are the two types of mixtures

homogeneous and heterogeneous mixtures

what is a homogeneous mixture

a mixture with a uniform composition throughout, in a single phase and cannot be separated easily. Often called solutions

what is a heterogeneous mixture

a mixture with a non-uniform composition, has different states which are not uniformly distributed.

what are the main states of matter

solid, liquid, gas

what is a phase change

a physical change where matter changes between states

what are fluids

substances that can flow and occupy the space they are in. Liquids and gases.

what are the 2 types of changes that matter an undergo

physical changes and chemical changes

physical change

a change in form or state that does not alter chemical composition

chemical change

a change where substances are transformed into new chemical species through a reaction

structure of an atom

a central nucleus of protons (positive) and neutrons (neutral) surrounded an electrons (negative). most of the mass is in the nucleus, however the electron cloud is larger than the nucleus, but most of it is empty space (vacuum)

what is an ion

an atom or molecule with a net electric charge

what is a cation

positively charged ion (lost electrons)

anion

a negatively charges ion (gained electron)

what is an isotope

atoms of the same element that have the same number of protons but different number of neutrons, resulting in different mass numbers. Can be radioactive → have an unstable nucleus and undergoes spontaneous decay

what is a molecule

a collection of two of more atoms chemically bonded together

what are reactants

starting substances in a chemical reaction

what happens during a chemical reaction

chemical bonds are broken and/or formed

what are products

new substances formed from a chemical reaction

Law of conservation of mass

mass is neither created nor destroyed in a chemical reaction

Law of definite proportions

a compound always has the same elements in the same ratio by mass

Atomic Number

symbol Z. the number of protons in the nucleus, identifies the chemical element.

Mass number

Symbol A. The total number of protons + neutrons

the atomic mass unit

It is 1/12 the mass of a carbon-12 atom. u = 1.66054 × 10⁻²⁷ kg

what is the atomic mass of an element (relative atomic mass)

the weighted average mass of naturally occurring isotopes of an element.

What is light

a form of energy and electromagnetic radiation, travels as waves

characteristics of waves

wavelength(λ) the distance between two peaks of a wave. in metres

frequency(v): number of waves passing a point per second (measures in Hz or s⁻¹

What are the two key equations for light and waves?

change in energy = hv (Planck’s constant? x frequency
change in energy = hc / λ (Planck’s constant x speed of light / wavelength)

speed of light

symbol c. 2.999 × 10⁸ m/s.

planck’s constant

symbol h = 6.626x10^-34

what is a continuous spectrum.

A spectrum that contains all wavelengths of light with no gaps (a full range of colours)

What is a line spectrum?

A spectrum that contains only specific wavelengths (lines), not a continuous range.

what is an emission spectrum

a type of line spectrum. Light emitted by excited atoms as electrons fall to lower energy levels. every element has a pattern of colours unique for that element.

Bohr Model of Atom

• electrons move in fixed circular orbits around the nucleus

• each orbit with integer n

• higher n = higher energy and larger orbit

• each orbit can only hold 2n² electrons

• when electrons move between orbits, light gets emitted/absorbed by atoms

Bohr energy equation for hydrogen like atoms (one electron)

Eₙ = −2.179 × 10⁻¹⁸ J × (1 / n²)

Quantum Mechanical Model

• probability of finding electrons in regions around the nucleus

• model has shells, subshells and orbitals

• orbital: place that can hold 2 electrons

• subshell: group of orbitals, hold 1 or 3 or 5 or 7 orbitals

• shell: collection of subshells

what is an orbital

region of space where up to 2 electrons are likely to be found. a probability distribution.

how does there quantum model differ from Bohr’s model

• electrons do not move in orbits, but exist in probability clouds/orbits

what are shells labelled as

n = 1,2,3…

what are the subshell types?

s = 1 orbital, 2 electrons

p = 3 orbitals, 6 electrons

d = 5 orbitals, 10 electrons

f = 7 orbitals, 14 electrons

g = 9 orbitals, 18 electrons

probability cloud.

orbitals have different shapes, electrons are most likely to be found in some regions than others.

many dots = electron likely to be

no dots = electron unlikely to be

Bohr vs Quantum

Bohr: line emission spectrum for hydrogen like atoms = one electron systems, simpler energy calculation

Quantum: more than one electron, describes probability clouds and not fixed orbits. Describes electron configuration with detail. Mathematically complex and hard to visualise.

Thompson/Plum Pudding Model

Electrons embedded in a positively charged sphere. Did not include a nucleus. Could not explain why alpha particles passed through gold foil with minimal deflection (thus positive charge must be concentrated not diffused)

Rutherford’s gold foil experiment

• Used alpha (very positive) particles to pass through a gold foil

• most particles passed straight through, small number deflected

• conclusion: most atom is empty space with a small positively charged central nucleus

Naming covalent compounds

• first element keeps its full name

• suffix -ide

• use prefixes to show number of atoms