YR9- Chemistry-Atomic structure and the periodic table

Alkali Metal

Elements in Group 1 of the periodic table

Atom

The smallest part of an element that can still be recognised as that element

Atomic Number

The number of protons in an atom

Electron

A tiny particle with a negative charge. Electrons orbit the nucleus of atoms or ions in shells

Electonic Stucture

A set of numbers to show the arrangement of elecrons in their shells

Element 

A substance made up of only one type of atom. An element cannot be broken down chemically into any simpler substance.

Group

All the elements in the columns (labelled 1 to 7 and 0) in the periodic table

Halogens

The elements found in Group 7 of the periodic table

Ion

A charged particle produced by the loss or gain of electrons

Isotope

Atoms that have the same amunt of protons but different number of neutrons, i.e. they have the same atomic number but different mass number

Law of Conservation of Mass

The total mass of the product formed in a reaction is equal to the total mass of reactants

Mass Number

The number of protons plus the neutrons in the nucleus of an atom

Neutron

A dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge

Noble Gases

The very unreactive gases found in Group 0 of the periodic table . Their atoms have very stable electronic structures

Nucleus

The very small and dense central part of an atom that contains protons and neutrons.

Protons

A tiny positive particle found inside the nucleus of an atom

Shell

An area in an atom, around its nucleus, where electrons are found 

State Symbol

The abbreviations used in balanced symbol equations to show if reactants and products are solid (S), liquid(L), gas (G) or dissolved in water (aq)

Transition Element

Element from the central block of the periodic table

Word Equation

A way of describing what happens in a chemical reaction by showing the names of all reactants and the products they form

Dalton

Atoms are solid spheres

Thomson

Plum Pudding Model-Descovers electrons and this model is a positive sphere with negative electrons scattered through it.

Rutherford

Proves Thompson’s model is wrong by firing alpha particles at gold atoms. Atoms have a small positive nucleus in the middle which can deflect alpha particles

Bohr

Discovers that electrons orbit the nucleus in shells

Chadwick

Discover that the nucleus containds neutrons as well as protons.