The How To of answering Bonding questions

QUESTION ONE: ELEMENTS OF THE PERIODIC TABLE

(a) (a) Explain the similarities and differences in the chemical reactivity of the elements fluorine and chlorine versus sodium and potassium. Link your answer to the electron configurations of each atom.

Comparing Fluorine and chlorine
Fluorine has an electron arangement of (2,7) and chlorine has an electron arrangement of (2,8,7). Both of these atoms are found in group 17 of the periodic table. This means that the both will react inthe same way, they need to gain one more electron to achieve a stable full valence shell. In doing so they become F- and Cl- ions. The difference between the two atoms is that they have different numbers of protons, neutrons and electrons and because the have different amounts of electron shells they belong to different periods of the periodic table. F is in period 2 and Cl is in Period 3.

Comparing sodium and potassium
Sodium has an electron arangement of (2,8,1) and Potassium has an electron arrangement of (2,8,8,1). Both of these atoms are found in group 1 of the periodic table. This means that the both will react in the same way, they need to lose one electron to achieve a stable full valence shell. In doing so they become Na+ and K+ ions. The difference between the two atoms is that they have different numbers of protons, neutrons and electrons and because the have different amounts of electron shells they belong to different periods of the periodic table. Na is in period 3 and K is in Period 4.


(b) Explain the differences in the chemical reactivity of the elements Fluorine and chlorine compared to sodium and potassium. Link your answer to the electron configuration of each atom.
Both fluorine and chlorine have 7 valence electrons F (2,7) and Cl(2,8,7). These atoms will gain one electron during a chemical reaction to achieve a full valence shell and become stable F- and Cl- ions.

Sodium and potassium both have one valence electron Na (2,8,1) and K(2,8,8,1) and so will lose this electron during a chemical reactions to achieve a full valence shell and become stable Na+ and K+ ions.



QUESTION TWO: COMPOUNDS OF Oxygen

(a) Discuss the melting point of solid lithium oxide, Li2O(s), and gaseous oxygen, O2 (g).
Your answer should include:
• which compound has the higher melting point
• the type of particle found in each compound
• the attractive forces in each compound
• the strength of those forces.
Lithium oxide is an ionic solid made up of lithium ions and oxide ions bonded together in a 3D lattice. These ions are bonded together by an ionic bond that is very strong and hard to break requiring large amounts of energy to break, so lithium chloride will have a higher melting point than oxygen.
Oxygen is a covalent compound that is made up of strong covalent bonds within the molecules, however the molecules are held together by weak intermolecular forces that do not require much energy to break. This means that oxygen has a very low melting point

QUESTION THREE: CONDUCTIVITY

Methane CH3, and lithium chloride, LiCl, are compounds. Discuss which of these substances is more likely to conduct electricity.
Your answer should include:
• What is needed for a substance to conduct electricity
• which compound will conduct electricity
• the type of particle found in each compound

Methane is a simple covalent compound made up of covalently bonded atoms that share electrons. these electrons are not free to move so methane cannot conduct electricity.
LiCl is an ionic substance that is made up of Li+ ions ans Cl- bonded together by a stron electrostatic attraction. These ions are not free to move in the solid LiCl, however they are free to move when LiCl is melted of dissolved in water. This means that LiCl will conduct electricity in these cases are the ions (charged paritcles) are free to move.