Chemistry - Unit 1 - Topic 1 - Atomic Structure

what is the relative mass of an electron?

1/1840

how are the protons and neutrons held in the centre of the atom?

• by a force called the strong nuclear force

• this force is much greater than the electrostatic forces of attraction that holds electrons and protons in place

• this force is significant so that the repulsion between protons in the nucleus is overcome 

• this force only acts over very short distances 

what is the atomic number of an element?

the number of protons in the nucleus of an atom

what is the mass number of an atom?

the total combined number of protons and neutrons in the nucleus of an atom

what is an isotope?

an isotope is an atom with the same number of protons but a different number of neutrons (to another)

how does an isotope of an element differ from another isotope?

• they will have the same chemical reactions as they have the same electron configuration

• physical properties may differ

what is the relative atomic mass of an element?

the average mass of an atom of an element relative to 1/12th the mass of an atom of carbon-12. 

what is the relative isotopic mass of an element?

the mass of a single isotope of an element relative to 1/12th the mass of an atom of carbon 12