Atoms, electrons and ions

Question 1

Where can electrons move to?

Answer 1

different energy levels, or they can leave the atom completely

Question 2

electrons in orbit

Answer 2

in all atoms, electrons orbit the nucleus at different energy levels at different, fixed distances from the nucleus

Question 3

moving between energy levels (3)

Answer 3

an electron will move from a lower to a higher orbit if it absorbs electromagnetic radiation

an electron will move from a higher to a lower orbit if it emits electromagnetic radiation

an electron can only absorb or emit a certain amount of radiation

Question 4

forming positive ions

Answer 4

atoms become positive ions when they lose electrons, as there are now more protons than electrons

Question 5

two ways an electron can leave an atom

Answer 5

• absorbing electromagnetic radiation of enough energy so that they can escape the pull of the nucleus (UV, Xrays or gamma)
• being hit by a particle such as an alpha or beta particle

Question 6

why can each electron only absorb certain frequencies/colours of light?

Answer 6

they have to move up a full energy level, so need at least a certain amount of energy

Question 7

emitting radiation (2)

Answer 7

• an electron needs to gain energy and move to a higher level before it can emit radiation
• an electron can only lose a fixed amount of radiation/energy - it can only emit certain frequencies or colours

Question 8

what happens if an electric charge is passed through atoms?

Answer 8

some electrons become delocalised, collide with other atoms and transfer energy to their electrons

Question 9

why do some gases burn with different colours?

Answer 9

different elements have different arrangements of electrons that can only emit a certain amount of energy, so the amount of energy/frequency or colour of light that each element emits will be different

Question 10

State the overall charge of an atom where an electron has moved from a higher to a lower orbit [1]

Answer 10

neutral or 0

no electron has been lost so there is no net charge in the atom

Question 11

Explain how ions are different from atoms [4]

Answer 11

atoms of an element contain the same number of protons as electrons and have a neutral charge overall

ions of an element have the same number of protons but can gain electrons so that they have a negative charge, or lose electrons so that they have a positive charge

Question 12

suggest how you could tell, by experiment, if an atom has become a positive or negative ion [2]

Answer 12

the charged particle is deflected in a magnetic field

a positive charge will move clockwise and a negative ion anticlockwise in the same magnetic field