Chapter 1.5

Question 1

what happens to atoms when they are heated?

Answer 1

give off electromagnetic radiation or light.

Question 2

what happens if light passes through the prism?

Answer 2

it produces a spectrum with a black background and a number of coloured lines.

Question 3

another name for these spectra

Answer 3

EMISSION SPECTRA (line spectra)
- related to the electronic structure within the atoms.

• each emission spectrum is unique for a particular element and can be used to identify different elements.

Question 4

emission spectrum

Answer 4

• each line in the spectrum corresponds to light of a different energy
• violet lines correspond to light with high energies
• as light changes to blue, green, yellow and orange, the energy of the light decreases.
• red light = lowest energy light visible to human eye.

Question 5

two important clues the emission spectrum produces about the electronic structure of atoms are?

Answer 5

1) atoms of the same element produce identical line spectra

2) each element has a unique line spectrum and therefore a unique electronic structure.

Question 6

who and when was the Bohr model created?

Answer 6

Niels Bohr and 1913

Question 7

what did Bohr do?

Answer 7

developed a new model of the hydrogen atom that explained emission spectra

Question 8

What are the four things the Bohr model proposed?

Answer 8

1) electrons revolve around the nucleus in fixed, circular orbits
2) the electrons’ obits correspond to specific energy levels in the atom
3) electrons can only occupy fixed energy levels and cannot exist between two energy levels.
4) orbits of larger radii corresponds to energy levels of higher energy.

in Bohrs model - its possible for electrons to move between the energy levels by absorbing or emitting energy in the form of light .

• gave close agreement between the calculated energies for lines in the hydrogen spectrum and the observed values in the spectrum.

Question 9

which electron shell has the lowest energy level and which one has the highest.

Answer 9

n = 1 (the shell closest to the nucleus) has the lowest energy level
WHEREAS
n =6 has the highest energy level (the valence or outer shell)

as the values of n increase, the energy levels get closer together.

Question 10

what does heating do to an electron?

Answer 10

causes an electron to absorb energy and jump to a higher energy state. shortly afterwards the electrons return to the lower energy state releasing a fixed amount of energy as light.

Question 11

light produced at different energy levels

Answer 11

lowest energy level to any = no light
3rd excited state to lowest = purple 
3rd to 2nd = pink 2nd to lowest = green
3rd to 2nd to first to lowest = pink, black, purple
3rd to 2nd to lowest = black, purple

Question 12

what is the ground state?

Answer 12

lowest energy state of an atom

Question 13

what is the excited state?

Answer 13

when the electron absorbs energy and jumps to a higher energy level.