Metals and non-metals in the periodic table
3 marks · EasyThis question is about similarities in chemical properties in groups and the inertness of Group 0 elements.
State the number of electrons in the outer shell of a fluorine atom.
Explain why the elements in Group 7 have similar chemical properties.
Explain why helium is unreactive.
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(a) 7
(b) Because all Group 7 elements have the same number of electrons (7) in their outer shell, causing them to react in similar ways. · must show Reference to same number of outer electrons, Relating that to similar reactions
(c) Helium is unreactive because it has a full outer shell (2 electrons), so it does not need to gain, lose, or share electrons. · must show Full/complete outer shell, No tendency to gain/lose/share electrons
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Marking points
B1 (a) · 1 mark · Correctly states '7' electrons in the outer shell of fluorine.
M1 (b) · 1 mark · Links similar chemical properties of Group 7 elements to their having the same number of electrons in the outer shell (7).
M1 (c) · 1 mark · States helium is unreactive because its outer shell is full (2 electrons), so it does not gain, lose, or share electrons.
Worked solution
a) Fluorine has 7 electrons in its outer shell.
b) Group 7 elements all have 7 electrons in their outer shell. This means they react in similar ways.
c) Helium is unreactive because its outer shell is full (2 electrons), so it does not need to gain, lose or share electrons.