Question

1. in general terms, what is a chemical bond?
2. the energy required to break a given chemical bond is called the _.
3. what sorts of elements react to form ionic compounds?
4. in general terms, what is a covalent bond?
5. compare and contrast the bonding found in the h₂(g) and hf(g) molecules with that found in naf(s).
6. the relative ability of an atom in a molecule to attract electrons to itself is called _.
7. in each of the following groups, which element is the most electronegative? what is the least electronegative?

a. cs, ba, at
b. ba, sr, ra
c. o, rb, mg

1. on the basis of the electronegativity values given on the table handed out in class, indicate whether each of the following bonds would be expected to be nonpolar covalent, polar covalent, or ionic bond.

a. s - s
b. s - h
c. k - s

1. for each of the following numbers of electrons, give the formula of a positive ion that would have that number of electrons, and write the complete electron configuration for each ion.

a. 10 electrons
b. 18 electrons
c. 36 electrons
d. 2 electrons

Explanation:

1. A chemical bond is the force that holds atoms together in a substance, resulting from the sharing or transfer of electrons.
2. The energy to break a chemical bond is bond - energy.
3. Ionic compounds are formed from the reaction of metals and non - metals. Metals lose electrons to form cations and non - metals gain electrons to form anions.
4. A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms.
5. In \(H_2\), there is a non - polar covalent bond as the two hydrogen atoms have the same electronegativity and share electrons equally. In \(HF\), there is a polar covalent bond due to the difference in electronegativity between hydrogen and fluorine, with the electrons being more attracted to fluorine. In \(NaF\), there is an ionic bond as sodium (a metal) donates an electron to fluorine (a non - metal) to form ions that are held together by electrostatic forces.
6. The relative ability of an atom in a molecule to attract electrons to itself is called electronegativity.

7.

• a. Among \(Cs\), \(Ba\), and \(At\), \(At\) is the most electronegative and \(Cs\) is the least electronegative.
• b. Among \(Ba\), \(Sr\), and \(Ra\), \(Sr\) is the most electronegative and \(Ra\) is the least electronegative.
• c. Among \(O\), \(Rb\), and \(Mg\), \(O\) is the most electronegative and \(Rb\) is the least electronegative.

8.

• a. \(S - S\) is a non - polar covalent bond as the two sulfur atoms have the same electronegativity and share electrons equally.
• b. \(S - H\) is a polar covalent bond due to the difference in electronegativity between sulfur and hydrogen.
• c. \(K - S\) is an ionic bond as there is a large difference in electronegativity between potassium (a metal) and sulfur (a non - metal).

9.

• a. A positive ion with 10 electrons is \(Na^+\). Its electron configuration is \(1s^22s^22p^6\).
• b. A positive ion with 18 electrons is \(K^+\). Its electron configuration is \(1s^22s^22p^63s^23p^6\).
• c. A positive ion with 36 electrons is \(Rb^+\). Its electron configuration is \(1s^22s^22p^63s^23p^63d^{10}4s^24p^6\).
• d. A positive ion with 2 electrons is \(Li^+\). Its electron configuration is \(1s^2\).

Answer:

1. The force holding atoms together, from electron sharing or transfer.
2. Bond - energy
3. Metals and non - metals
4. Sharing of electron pairs between atoms
5. \(H_2\): non - polar covalent; \(HF\): polar covalent; \(NaF\): ionic
6. Electronegativity

7.

• a. Most: \(At\), Least: \(Cs\)
• b. Most: \(Sr\), Least: \(Ra\)
• c. Most: \(O\), Least: \(Rb\)

8.

• a. Non - polar covalent
• b. Polar covalent
• c. Ionic

9.

• a. \(Na^+\), \(1s^22s^22p^6\)
• b. \(K^+\), \(1s^22s^22p^63s^23p^6\)
• c. \(Rb^+\), \(1s^22s^22p^63s^23p^63d^{10}4s^24p^6\)
• d. \(Li^+\), \(1s^2\)