Define atomic number.
In 1913, atomic numbers were introduced by the young English scientist pictured on the right. Two years later he was killed in action at Galli... show full transcript
Worked Solution & Example Answer:Define atomic number - Leaving Cert Chemistry - Question 5 - 2009
Step 1
Define atomic number.
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Answer
The atomic number is defined as the number of protons in the nucleus of an atom of the same element.
Step 2
Who was he?
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The scientist referred to is Moseley.
Step 3
What is an ionic bond?
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Answer
An ionic bond is the attraction between oppositely charged ions in a crystal, which involves the loss and gain of electrons.
Step 4
How many protons are there (i) in the nucleus of the magnesium ion?
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The magnesium ion has 12 protons in its nucleus.
Step 5
(ii) in the nucleus of the oxide ion?
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The oxide ion has 8 protons in its nucleus.
Step 6
Copy the diagram into your answer book. Use dots and crosses to show the electrons present in each of the four shells.
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Answer
In the diagram, the electrons can be represented by placing dots for oxygen and crosses for magnesium in their respective shells.
Step 7
Give any two characteristic properties of ionic compounds.
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Ionic compounds typically have high melting points and can conduct electricity when molten.
Step 8
What term is used to describe the shape of this molecule?
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The term used to describe the shape of the methane molecule is 'tetrahedral'.
Step 9
What type of bond is present in the molecule?
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The type of bond present in methane is covalent.
Step 10
Give the name or molecular formula of any other simple molecule.
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Answer
An example of another simple molecule is water, with the molecular formula H₂O.
Step 11
Draw the shape of its molecules or give the term that describes the shape.
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The shape of the water molecule is V-shaped.
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