Which is visible to the naked eye?
A. atoms
B. chemical bonds
C. attractive forces
D. substances that atoms make up

Which is the most accurate description of ionic and covalent bonding?
A. Both bonds happen when valence electrons are shared between atoms.
B. Both bonds happen when valence electrons are transferred between ions.
C. Ionic bonds happen when valence electrons are transferred between ions, while covalent bonds happen when valence electrons are shared between atoms.
D. Ionic bonds happen when valence electrons are shared between atoms, while
covalent bonds happen when valence electrons are transferred between ions.

Calcium has an atomic number of 20.
How many electrons of a calcium atom are involved in chemical bonding?
A. 2
B. 8
C. 16
D. 20