Question

ionic and covalent bonding review
a calcium atom has type here valence
electrons. it needs to transfer type here
electrons to oxygen to have a full outer
shell. an oxygen atom has type here
valence electrons. it needs to accept
type here electrons from calcium to have
a full outer shell.
calcium (ca)
oxygen (o)
images of ca and o atomic structures

Explanation:

Step1: Determine Calcium's valence electrons

Calcium (Ca) has an atomic number of 20. Its electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2\). The outermost shell (4th shell) has 2 electrons, so calcium has 2 valence electrons. To achieve a full outer shell (like a noble gas, which has 8 electrons in the outer shell for main - group elements, or 2 for the first shell), calcium, being a metal, tends to lose its valence electrons. Since it has 2 valence electrons, it needs to transfer 2 electrons.

Step2: Determine Oxygen's valence electrons

Oxygen (O) has an atomic number of 8. Its electron configuration is \(1s^2 2s^2 2p^4\). The outermost shell (2nd shell) has \(2 + 4=6\) electrons. A full outer shell for the 2nd shell requires 8 electrons. So, oxygen needs to accept \(8 - 6 = 2\) electrons to have a full outer shell.

Answer:

A calcium atom has \(\boldsymbol{2}\) valence electrons. It needs to transfer \(\boldsymbol{2}\) electrons to oxygen to have a full outer shell. An oxygen atom has \(\boldsymbol{6}\) valence electrons. It needs to accept \(\boldsymbol{2}\) electrons from calcium to have a full outer shell.