Chemistry topic test 2

yr 10 2026

Dalton

proposed first atomic theory, said that matter was composed from small, invisible, indestructible atoms and all atoms of the same element had the same mass and properties

Thomson

proved atom was divisible by using a cathode ray tube experiment where he demostrated that the rays were made from negatively charged particles which were later known as electrons

Perrin

gave experimental proof to show atomism where he verified Einstein's theories, confirming that suspended particles behaved as if they were struck by moving molecules

Mendeleev

organised the 63 known elements onto the periodic table by increasing atomic weight and their chemical properties

Rutherford

conducted the 'gold foil experiment', showing atoms were mainly empty space save for the center, proposing the nuclear model

Mosley

refined the periodic table by organising them by increasing atomic number as he discovered the frequency of X-rays is directly proportional to the square of a specific integer, which was identified as the atomic number

Aston

provided proof that atomic weight were not always whole numbers as he invented the mass spectrograph which could separate and weigh atoms

Bohr

proposed that electrons occupy fixed, quantised energy levels rather than orbiting randomly, providing a theoretical foundation for the periodic table's electron configuration

Chadwick

discovered a neutral particle that almost had the same weight as the proton which he later named the neutron

period number

how many electron shells an atom has

group number

how many valence elecrtons an atom has

reactivity

elements with nearly full/empty shells valence electron shells

valency

combining capacity of an atom, determined by the number of electrons an atom gains or loses to achieve a stable electron configuration

valence electrons

electrons on the outermost electron shell

ionic bond

combining a non-metal with a metal. the metal transfers its electrons to the non-metal, allowing them both to have stable electron configurations

ionic compounds

NaCl, CaCO3

covalent bond

combining 2 non-metals together. they share electrons, allowing them both to have stable electron configurations

molecular compounds

H2O, CO2

neutralisation

acid + base --> salt + water

neutralisation def

when an acid and base react with each other forming a neutral substance

combustion

hydrocarbon + oxygen gas --> water + carbon dioxide

combustion def

the exothermic oxidation of a substance

displacement

when a more reactive element displaces a less reactive element in a compound

single displacement

AB + C --> AC + B

double displacement

AB + CD --> AD + BC

oxidation

loss of electron, addition of oxygen to a substance

oxidation example

H --> H+

reduction

gain of electrons, removal of oxygen to a substance

reduction example

Cl --> Cl-

precipitate

insoluble solid that emerges from 2 aqueous solutions

observation

using senses or information to gather data on substances and chemical reactions

hypothesis

prediction of what will happen in the experiment based on limited knowledge

inference

logical conclusion made by combining evidence with knowledge

mole

amount of a substance, is substance's relative atomic/formula mass in grams

Avogadro's constant

6.022 x 10^23

atomic number

number of protons

atomic mass

weighted average mass of an atom or element

molar mass

mass of atoms or compounds