How does the number of valence electrons of an atom to determine whether an atom is likely to form ionic or covalent bonds?

The number of valence electrons is important to know when determining the type of bond between atoms. This is because ionic bonds transfer electrons to fill in the electron shell. For example if we have a Na atom with 1 valence electron and a Cl atom with 7 valence electrons that 1 electron will transfer to Cl to fill the electron shell.
In contrast, Covalent bonds share electrons.
And Just a Tip: Covalent bonds are between two non-metals. Ionic bonds are between a non-metal and a metal.
Hope this helped(:

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer