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distinguish between mass number and relative atomic mass of an element - Leaving Cert Chemistry - Question 5 - 2013
Question 5
distinguish between mass number and relative atomic mass of an element. You will notice, from the values given on page 79 of the formulae and tables booklet, that t... show full transcript
Worked Solution & Example Answer:distinguish between mass number and relative atomic mass of an element - Leaving Cert Chemistry - Question 5 - 2013
Step 1
Distinguish between mass number and relative atomic mass of an element.
Answer
The mass number is defined as the total number of protons and neutrons within an atomic nucleus. It reflects the mass of the nucleus and is a whole number, as it counts the individual nucleons present.
On the other hand, relative atomic mass is the weighted average mass of an atom of an element compared to the mass of a carbon-12 atom. This value incorporates the average masses of isotopes and accounts for the abundance of each isotope. Thus, relative atomic mass is often not a whole number because it averages the masses of various isotopes.
Step 2
Step 3
Step 4
Explain the underlined term.
Answer
Beta-particle refers to a high-speed electron (e⁻) that is emitted during the radioactive decay of an unstable atomic nucleus. It is typically generated as a result of beta decay, where a neutron is converted into a proton, releasing the beta-particle and an antineutrino.
Step 5
Explain what is meant by the half-life of a radioactive isotope.
Answer
The half-life of a radioactive isotope is the time required for half of the radioactive sample to decay into its daughter products. It provides a measure of the rate at which a radioactive substance undergoes decay, usually expressed in years, hours, or minutes depending on the isotope.
Step 6
Step 7
Draw a diagram showing the arrangement of electrons in an atom of carbon-14.
Answer
To depict the arrangement of electrons in a carbon-14 atom, we represent the nucleus containing 6 protons and 8 neutrons at the center. The electrons, which number 6 in total, are drawn in two shells around the nucleus: 2 electrons in the first shell and 4 in the second shell, using dots (•) or crosses (x). The diagram is as follows:
••
•
x x
•• ••
(Note: The representation would ideally be a visual diagram, but it is often simplified for text-based formats.)