EL1

Question 1

atomic number

Answer 1

number of protons in the nucleus of an atom

Question 2

mass number

Answer 2

number of protons+neutrons in the nucleus of an atom

Question 3

relative isotopic mass

Answer 3

relative mass of an isotope, relative to 1/12 of the mass of a carbon-13 atom

Question 4

ancient greek

Answer 4

matter is made from indivisible particles

Question 5

Dalton

Answer 5

atoms are solid particles

Question 6

JJ Thompson

Answer 6

atoms contain small, negatively charged particles. “plum pudding” model suggest atom is a positively charged sphere with negative electrons embedded in it

Question 7

Rutherford (G&M)

Answer 7

the atom has a tiny positively charged nucleus surrounded by free electrons and the atom is mostly empty space

Question 8

Bohr

Answer 8

used the emission spectra to predict how electrons are arranged
-they exist in fixed shell
-each shell has a fixed energy
-electromagnetic radiation is emitted or absorbed when electrons move between shells
-the radiation has fixed frequencies

Question 9

Chadwick

Answer 9

discovers neutron

Question 10

Geiger Marsden experiment

Answer 10

-positively charged alpha particles fired at very thin gold foil
-most alpha particles passed through (most of the atom is empty space)
-some alpha particles were deflected through large angles (tiny, positively charged nuclei)

Question 11

relative atomic mass (Ar)

Answer 11

average weighted mass of the isotopes of an element, taking into account the percentage abundance of each isotope

Question 12

formula of Ar

Answer 12

Question 13

isotopes

Answer 13

atoms of an element with same numbers of protons but different numbers of neutrons

Question 14

nuclear fusion

Answer 14

E=MC^2
lighter nuclei joining to give heavier nuclei.
This happens in stars because very high temperatures and pressures are required to overcome the repulsion between positively charged nuclei

Question 15

ions

Answer 15

a positively or negatively charged atom on covalently bonded group of atoms