Elements of life Flashcards
EL)w)v)
What is the flame colour for the flame test of the metal cation Li+
- Bright red
EL)w)v)
What is the flame colour for the flame test of the metal cation Na+
- Orange
EL)w)v)
What is the flame colour for the flame test of the metal cation K+
- Lilac
EL)w)v)
What is the flame colour for the flame test of the metal cation Ca2+
- Brick red
EL)w)v)
What is the flame colour for the flame test of the metal cation Ba2+
- Apple green
EL)w)v)
What is the flame colour for the flame test of the metal cation Cu2+
- Blue green
EL)v)
What is the electromagnetic spectrum in order of increasing frequency?
- Radiofrequency
- Microwave
- Infrared
- Visible light
- Ultraviolet
- X-ray
- Gamma ray
EL)v)
What is the electromagnetic spectrum in order of increasing energy?
- Radiofrequency
- Microwave
- Infrared
- Visible light
- Ultraviolet
- X-ray
- Gamma ray
EL)v)
What is the electromagnetic spectrum in order of decreasing frequency?
- Gamma ray
- X-ray
- Ultraviolet
- Visible light
- Infrared
- Microwave
- Radiofrequency
EL)v)
What is the electromagnetic spectrum in order of decreasing energy?
- Gamma ray
- X-ray
- Ultraviolet
- Visible light
- Infrared
- Microwave
- Radiofrequency
EL)v)
What is the electromagnetic spectrum in order of increasing wavelength?
- Gamma ray
- X-ray
- Ultraviolet
- Visible light
- Infrared
- Microwave
- Radiofrequency
EL)v)
What is the electromagnetic spectrum in order of decreasing wavelength?
- Radiofrequency
- Microwave
- Infrared
- Visible light
- Ultraviolet
- X-ray
- Gamma ray
EL)g)
Chemists have put forward various models to try to explain atomic structures. Scientific models often change in the light of new evidence.
The diagrams below show possible structures for atoms based on different models, A-D.
Match each statement with the appropriate corresponding model.
- Dalton suggests from experiments with gases that atoms are ‘indivisible’ and react in whole numbers
- Thompson discovers the negatively charged electron
- Rutherford, Geiger and Marsden find that some positively charged α particles bounce almost straight back when fired at a thin metal foil
- Excited atoms emit light which forms a line emission spectrum
- C
- B
- A
- D
EL)g)
The current model of the atom describes a nucleus containing protons and neutrons surrounded by electrons in energy levels.
Complete the following table showing the properties of the sub-atomic particles
- relative mass of proton = 1
- relative charge of proton = +1
- relative mass of neutron = 1
- relative charge of neutron = 0
- relative mass of electron = 0.0005
- relative charge of electron = -1
EL)a)
Explain why:
- mass numbers of atoms are always whole numbers
- the relative atomic mass of an element may not be a whole number
- mass number = protons + neutrons
- protons and neutrons both have a relative mass of 1, and electrons have a negligible mass, therefore mass number is always whole
- relative atomic mass of an element (Ar) is only an average
- of naturally occuring isotopes
- therefore may not be a whole number
EL)h)
Geiger and Marsden used the radioactive isotope 226Ra in their experiments. 226Ra decays by α-emission.
Write a nuclear equation for this process.
EL)w)ii)
Much of our knowledge of outer space is based on spectroscopic data.
Absorption spectra give information about the elements present in starts.
Describe the main features in the appearance of an atomic absorption spectrum.
- continuous coloured visible spectrum background
- black lines
- that get closer together at higher frequency
EL)w)ii)
What are the similarities and differences between an atomic emission spectrum’s appearance and an absorption spectrum?
- Similarities
- lines positioned in the same place for a given element
- lines become closer at higher frequencies
- series of lines representing transitions to or from a particular energy level
- Differences
- coloured lines
- black background
EL)i)
Radiowaves can provide information about the molecules found in some regions of space. One molecule found in the coldest regions of outer space has the formula H2CO. This molecule is represented in the diagram below
Draw the ‘dot-and-cross’ diagram for this molecule
- Diagram must have
- two lone pairs on oxygen
- two crosses and two dots between C and O
- dot and cross between each C and H
EL)k)
Use the diagram below of H2CO to help you describe and explain its shape, giving the bond angle.
- bond angle = between 118-122
*
EL)g)
There has been a steep rise in demand in recent years for the isotope helium-3. This isotope is used widely in cold temperature research and medical imaging.
Complete the following table to show the atomic structures of helium-3 and helium-4.
- Number of protons
- Helium-3 = 2
- Helium-4 = 2
- Number of neutrons
- Helium-3 = 1
- Helium-4 = 2
- Number of electrons
- Helium-3 = 2
- Helium-4 = 2
EL)h)
There has been a steep rise in demand in recent years for the isotope helium-3. This isotope is used widely in cold temperature research and medical imaging.
Helium-3 is also formed in the Sun by nuclear fusion processes involving isotopes of hydrogen.
Write the nuclear fusion equation for the production of helium-3 from two different isotopes of hydrogen.
EL)h)
Nuclear fusion processes could be a useful energy source. It is very difficult, however, to create the high temperatures and pressures to bring about safe fusion on Earth.
Suggest why very high temperatures and pressures are needed for nuclear fusion.
- To overcome repulsion
- between two postively charged nuclei
- in order to join the nuclei to make a heavier nuclei
EL)w)ii)
The presence of helium in the Sun was detected when its atomic absorption spectrum was recorded during a solar eclipse.
Describe the appearance of an atomic absorption spectrum.
- continuous coloured visible spectrum background
- black lines
- lines getting closer at higher frequency
