AS Chem - Elements of Life

  • Created by: KHill
  • Created on: 18-11-14 11:41
Define isotope
Atoms of the same element with the same no. of p+ but different no. of neutrons.
1 of 45
Isotopes with higher mass have...
...Higher mass, density, mp and bp. Also slower rates of diffusion. However they have the SAME chemical reactivity.
2 of 45
Cl occurs naturally w/ 75% Cl-35 and 25% Cl-37. What is the RAM of Cl?
((35 x 75) + (37 x 25)) / 100 = 35.5
3 of 45
Define Radioisotope
Isotopes have unstable nuclei which breakdown .'. are RADIOACTIVE
4 of 45
Name 3 kinds of emissions
Alpha; Beta; Gamma
5 of 45
Describe ionisation of an atom
Emissions knock e-s out of atom they collide with
6 of 45
Alpha particles are like...
4/2 He nuclei
7 of 45
Write the Nuc. Eqn of Alpha Decay of U-283
238/92-U --> 234/90-Th + 4/2-He
8 of 45
Beta particles are like...
A single e-
9 of 45
Write the Nuc. Eqn of Beta Decay of C-14
14/6-C --> 14/7-N + e-
10 of 45
Which particle converts to another during Beta decay?
A neutron is converted to a p+
11 of 45
What does Gamma decay emit?
Energy from the nucleus changing from a high level to a lower one.
12 of 45
Radioisotopes used as tracers should...
...Be gamma emitters to minimise ionisation of cells; Have short H-L to minimise harm to patient
13 of 45
Describe the conditions for Nuc. Fusion
Vry high temps (nuclei must have enough energy to move more quicjly & collide with enough energy to overcome repulsion of +ive nuclei); 2 nuclei must be very close so that strong nuclear forces holding 'p+'s & neutrons fuse nuclei together
14 of 45
Where do fusion reactions take place?
In gas clouds (to form new elements), where the energy causes the clouds to glow
15 of 45
At high temps in gas clouds 'e-'s have enough energy to....
....escape nuclei
16 of 45
Describe plasma
Gases existing in an ionised form, in which +ive nuclei exist in a sea of delocalised 'e-'s
17 of 45
What are the problems with attempting to harness fusion reactions for electricity production?
Difficult to safely generate & contain plasma at high temps needed (+10 to 7 degrees C) and make process sustainable & economic
18 of 45
Each nucleus in a sample of an isotope decays... random
19 of 45
In a compund or in a free state, Uranium would decay... the same way
20 of 45
As more nuclei in a sample decay, the sample becomes....
....less radioactive
21 of 45
Define Half-Life
The time for half of the nuclei in a sample to decay
22 of 45
Sample of radioisotope has count rate of 52 counts/min & 4hrs later is 13 counts/min. Calculate the H-L
After 1 H-L the count rate would be 26 .'. after 2 H-Ls it would be 13 .'. 2H-LS = 4hrs so 1H-L = 2hrs
23 of 45
H-L can be used to calc...
...time for activity/mass of isotope to fall to a certain value; Mass of isotope/its activity after its decayed for a certain time
24 of 45
Meteors are composed similarly to earth and are similar age suggesting...
...they formed aroun the same time as the solar system .'. earth formed around 4.6 bill yrs ago
25 of 45
Ratio of C-12:C-14 in living org.s doesn't change but after death C-14 not replenished so ratio..
...increases '.' amount of C-12 increases
26 of 45
If ratio of C-12;C-14 can be measured...
...age of material can be estimated
27 of 45
Remains older than 50,000yrs old cannot be dated '.' ...
...Remaining amount of C-14 is difficult to measure .'. errors become too large for sensible range to be produced
28 of 45
Define spectroscopy
Study of how light & matter interact
29 of 45
Light is one form of ? radiation
30 of 45
The speed of light (C) is ? for all kinds of light when travelling in a vacuum
The SAME or 3.00 x 10to8 ms-1
31 of 45
What is the equation for the constant or speed of light?
Wavelength x Frequency = Constant (Speed of light)
32 of 45
Behaviour of light is easier to explain when you think in terms of...
33 of 45
The particle theory of light regards light as...
...a stream of tiny 'packets' of energy (Photons)
34 of 45
The energy of Photons is related to...
....the position of the light in the elec.mag. spec
35 of 45
The 2 theories of light (wave and photon/particle models) are linked by...
E=hv (Energy of photon = frequency x Planck constant)
36 of 45
What is the value of the Planck constant?
6.63 x 10to-34 J/Hz
37 of 45
There are 2 atomic spectra. Name them.
Emission spectrum and Absorption spectrum
38 of 45
Atoms become 'excited' by ? energy and when they lose energy they return to their ? ?
absorbing.........Ground state
39 of 45
Energy is usually emitted as ? ? and can be split into the atomic spectrum by ? ? ?
elec.mag. radiation........passing it through a prism/diffraction grating
40 of 45
An emission spectrum is caused by....
....light emitted by excited atoms
41 of 45
In the visible region, the spectrum consists of ? lines on a ? background
42 of 45
A continuous spectrum cannot be produced from an emission spectrum because....
....atoms only emit certain (precise) frequencies
43 of 45
An Absorption spectrum is caused by...
...light absorbed by atoms
44 of 45
During absorption, when white light passes through a sample ? lines appear on a
45 of 45

Other cards in this set

Card 2


...Higher mass, density, mp and bp. Also slower rates of diffusion. However they have the SAME chemical reactivity.


Isotopes with higher mass have...

Card 3


((35 x 75) + (37 x 25)) / 100 = 35.5


Preview of the back of card 3

Card 4


Isotopes have unstable nuclei which breakdown .'. are RADIOACTIVE


Preview of the back of card 4

Card 5


Alpha; Beta; Gamma


Preview of the back of card 5
View more cards


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Elements of Life resources »