topic 1 definitions

Question 1

atomic number

Answer 1

number of protons in the nucleus of an atom

Question 2

mass number

Answer 2

sum of number of protons and neutrons in the nucleus of an atom

Question 3

isotopes

Answer 3

atoms of the same element with the same number of protons but different number of neutrons in the nucleus

Question 4

relative atomic mass

Answer 4

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

Question 5

relative molecular mass

Answer 5

average mass of an atom of a molecule relative to 1/12th the mass of an atom of carbon-12

Question 6

relative isotopic mass

Answer 6

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

Question 7

quantum shells

Answer 7

same as electron shells, however they specify the energy level of an electron

Question 7

first ionisation energy

Answer 7

the energy required to remove 1 mole of electrons from each ion in 1 moles of gaseous 1+ ions to form 1 moles of gaseuos 2+ ions

Question 8

orbital

Answer 8

a region in an atom that can hold up to two electrons with opposite spins

Question 8

periodicity

Answer 8

trends in element properties with increasing atomic number

Question 8

Hund’s rule

Answer 8

when electrons fill the orbitals, they occupy them singly before they pair up

Question 9

isoelectronic

Answer 9

the total output of goods and services produced in a country.

Question 10

Pauli Exclusion Principle

Answer 10

electrons within the same orbital must have opposite spins

Question 11

Aufbau Principle

Answer 11

as the atomic number increases the electrons are added to orbitals in order of increasing orbital energy until all electrons are accommodated

Question 12

shielding

Answer 12

a decrease in the nuclear charge experienced by an outer shell electron caused by electron-electron repulsion between the outer shell electron and electrons from adjacent quantum shells