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5. (a) Define electronegativity - Leaving Cert Chemistry - Question 5 - 2008
Question 5
5. (a) Define electronegativity. (b) State and explain the trend in electronegativity values down the first group in the periodic table of the elements. (c) Use el... show full transcript
Worked Solution & Example Answer:5. (a) Define electronegativity - Leaving Cert Chemistry - Question 5 - 2008
Step 1
Step 2
State and explain the trend in electronegativity values down the first group in the periodic table of the elements.
Answer
The trend in electronegativity values down the first group of the periodic table is that electronegativity decreases.
This decrease is explained by the increasing atomic radius as you move down the group. Each element has an extra electron shell, which places the outer electrons further from the nucleus. Consequently, the effective nuclear charge experienced by these outer electrons is reduced due to increased shielding (screening) by the inner shells of electrons. The lower electronegativity values represent a weaker attraction for shared electrons.
Step 3
Use electronegativity values to predict the types of bonding (i) in water, (ii) in methane, (iii) in magnesium chloride.
Answer
(i) In water (H₂O), the bonding is polar covalent due to the difference in electronegativity between hydrogen and oxygen.
(ii) In methane (CH₄), the bonding is covalent, and the molecule is non-polar due to the similar electronegativities of carbon and hydrogen.
(iii) In magnesium chloride (MgCl₂), the bonding is ionic, as there is a significant difference in electronegativity between magnesium and chlorine.