1.1: A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

Question 1

What is an atom?

Answer 1

An atom is the smallest part of an element that can exist. Atoms make up all substances.

Question 2

How are compounds formed?

Answer 2

Compounds are formed from elements by chemical reactions.

(Chemical​ ​reactions always​ ​involve​ ​the​ ​formation​ ​of​ ​one​ ​or​ ​more​ ​new​ ​substances,​ ​and​ ​often​ ​involve​ ​an energy​ ​change.)

Question 3

What are compounds?

Answer 3

Compounds​ ​are when​ ​two​ ​or​ ​more​ ​elements are​ ​chemically​ ​combined​ ​in​ ​fixed​ ​proportions.

Question 4

What is a mixture?

Answer 4

A​ ​mixture​ ​consists​ ​of​ ​two​ ​or​ ​more​ ​elements​ ​or​ ​compounds​ ​not​ ​chemically​ ​combined
together.​ ​

(different to a compound)

Question 5

How can mixtures be separated?

Answer 5

Can​ ​be​ ​separated​ ​by:​ ​filtration,​ ​crystallisation,​ ​simple​ ​distillation,​ ​fractional​ ​distillation and​ ​chromatography.​ ​

These​ ​are​ ​physical​ ​processes,​ ​so​ ​do​ ​not​ ​involve​ ​chemical​ ​reactions and​ ​no​ ​new​ ​substances​ ​are​ ​made.

Question 6

What is the atomic number of an element?

Answer 6

The​ ​number​ ​of​ ​protons​ ​in​ ​an​ ​atom​ ​of​ ​an​ ​element.

(An atom has an overall charge of 0. So, the number of protons = number of electrons)

Question 7

What is the atomic mass number of an element?

Answer 7

The sum of the protons and neutrons in an atom.

Question 8

What is an isotope?

Answer 8

An isotope is an atom of the same element with different numbers of neutrons.

Question 9

What is the electronic structure of an atom like?

extended answer

Answer 9

Electrons occupy the​ ​lowest​ ​available​ ​energy​ ​levels​ ​(the​ ​shells​ ​closest​ ​to​ ​the​ ​central nucleus.)

Electronic​ ​structure​ ​of​ ​an​ ​atom​ ​tells​ ​you​ ​how​ ​many​ ​electrons​ ​are​ ​in​ ​each​ ​shell
e.g.​ ​for​ ​sodium:​ ​2​ ​electrons​ ​in​ ​shell​ ​1​ ​(closest​ ​to​ ​nucleus),​ ​8​ ​in​ ​shell​ ​2,​ ​1​ ​in​ ​shell​ ​3 Electronic​ ​structure=​ ​2,8,1