3E Chemistry_ Ionic and Covalent Compounds

Which of the following shows the formation of a sodium ion?

• Na → Na⁺ + e⁻

• Na⁺ + e⁻ → Na

• Na + e⁻ → Na⁺
  
  

• Na⁺ → Na + e⁻

What is a covalent bond?

• A bond formed between metal and non-metal ions
  
  

• A bond formed by the transfer of electrons from one atom to another

  
  

• A bond involving the delocalization of electrons

• A bond formed by the sharing of a pair of electrons between atoms

What type of elements typically form covalent bonds?

• Metals
  
  

• Metalloids

• Non-metals
  
  

• Noble gases

Which dot-and-cross diagram correctly represents the covalent bonding in a hydrogen molecule (H₂)?

• H⁺ + H⁻ → H–H
  
  

• H· + ·H → H:H
  
  

• H → H ←

• H· + H· → H··H

What is the structure of ionic compounds in solid state?

• A linear arrangement of atoms

• A three-dimensional giant ionic crystal lattice

• A random arrangement of molecules

• A single layer of atoms

Why do ionic compounds have high melting and boiling points?

• Low energy requirements to break bonds

• Strong covalent bonds

• Strong electrostatic forces of attraction

• Weak intermolecular forces

Which of the following describes the electrical conductivity of ionic compounds?

• They do not conduct electricity at all

• They conduct electricity in solid state

• They conduct electricity when dissolved in water

• They are good conductors in all states

What is the bonding structure in diamond?

• Covalent bonds in a three-dimensional network

• Covalent bonds in a two-dimensional layer

• Metallic bonds in a giant lattice

• Ionic bonds in a three-dimensional lattice

Which property of graphite allows it to conduct electricity?

• High melting point

• Weak intermolecular forces

• Strong covalent bonds

• Presence of mobile electrons

How many pairs of electrons are shared in an oxygen (O₂) molecule?

• 1

• 3

• 2

• 4