Atomic structure

Question 1

Define atom

Answer 1

The smallest part of an element which can not be further broken down by chemical means

Question 2

What do the below letter denote?
A - n
- X
Z

Answer 2

A - Mass number (protons + neutrons)
Z - Atomic number (protons)
X- Element
n - charge

Question 3

Define isotope

Answer 3

Atoms of the same elements with different number of neutrons in the nucleus

Question 4

Calculate the Ar of chlorine where Cl-35 is abundant as 75% and Cl-37 is abundant in 25%

Answer 4

[ (0.75 x 35 ) + (0.25 x 37) ] =35.5 g/mol

Question 5

Uses of Radioactive isotopes

Answer 5

Nuclear power generation
Sterilisation of surgical instruments
Finding cracks and and stresses in metal
Carbon dating with carbon -14
Radiotherapy with Co-60
Tracers in medicine with. I-125 and I-131

Question 6

Formula for velocity of a wave with units

Answer 6

c = v x y

c - m/s velocity
y - m wavelength
v -1/s frequency

Question 7

The order of the electromagnetic spectrum

Answer 7

Radio waves, Micro waves, Infrared, Visible light, Ultraviolet light, X-rays, Gamma radiation

Question 8

How does frequency, wave length and velocity change with the electromagnetic spectrum

Radio waves, Micro waves, Infrared, Visible light, Ultraviolet light, X-rays, Gamma radiation

Answer 8

Velocity is constant
Wavelength decreases from Radio to Gamma
Frequency increases from radio to gamma

Question 9

Which has a longer wave length, red or violet light?

Answer 9

Red light

Question 10

Which has a higher frequency, red or violet. light?

Answer 10

Violet light

Question 11

How can light be used to determine an element?

Answer 11

Each element has its own characteristic line spectrum as they have non continuous emission spectra

Question 12

Order of filling electron orbitals

Answer 12

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

Question 13

Electron configuration of Cu and Cr

Answer 13

Cu - [Ar] 4s1 3d5
Cr - [Ar]. 4s1 3d10

Question 14

Electron configuration of Cu+

Answer 14

Cu + = [Ar} 3d10

Question 15

When considering a transition element in the first row, from which orbital are electrons removed first

Answer 15

First 4s electrons are removed and then 3d electrons

Question 16

What is the shape of an S and P orbital

Answer 16

S - Spherical
P - Orthogonal

Question 17

Define first ionization energy of an element

Answer 17

The energy required to remove one mole of electrons from an atom in its gaseous state measure in kJ/mol

Question 18

Formula for energy required to remove one electron and one mole of electrons

Answer 18

E = hv = hc/y

c - the speed of light
y - wave length
v - frequency
h- planks constant 6.63 x 10^-34 J s

For one mole of electrons simply multiply by 6.02 x 10^23

Question 19

Explain emission and absrobtion spectra

Answer 19

As energy is supplied to an electron it reaches an excited state, and absorbs the photons of a specific wave length. This produces the black bands in absorption spectrum

As the electrons fall from sub levels they release energy in the form of photons producing the coloured lines in emission spectra

The larger the fall the more energy released thus when an electron falls to

n=1 ultra voilet is released
n=2 visible light is released
n=3 infrared is released

Question 20

Describe the hydrogen emission spectra

Answer 20

A series of lines only certain frequencies/wavelengths that show convergence at higher frequency/energy