Page 30 - Surviving Chemistry BFF Homework Helper and Test Prep Preview

Key Concept Definition and facts Key examples

Electrons in the outermost level of an atom.
The last number in a configuration is always
Sulfur 2 – 8 – 6 the number of valence electrons (for sulfur: 6).
A neutral atom may lose or share its valence e-, or

gain e- to fill up its valance shell during bonding.

Atoms with equal number of protons to electrons.

A neutral S atom has: 16 protons (+)
16 electrons (–)

Charged atoms with unequal numbers of protons
to electrons.

Formed by a neutral (metal) atom losing e-.
+
+

Na atom Na ion Na ion is formed when Na atom (a metal)
loses 1 electron.

A +ion always has fewer e- than the atom.
11+ 2 8 1
(c) E3 Scholastic Publishing
11+ 2 8
+
Na has 1 fewer electron than Na atom.

11+ protons 11+ A +ion always has more protons than electrons.
+
Na has more protons (11+) than electrons (10e-).
11 e- electrons 10 e-

2–8–1 electron 2–8 A +ion is always smaller than the atom.
configurations +
Na is smaller than Na atom.

Formed by a neutral (nonmetal) atom gaining e-.

2-
S ion is formed when S atom (a nonmetal)
2-

S atom S ion gains 2 electrons.

A –ion always has more e- than the atom.
S has 2 more electrons than S atom.

16+ 2 8 6 16+ 2 8 8 2-

A –ion always has fewer protons than electrons.
2-
16+ protons 16+ S has fewer protons (16+) than electrons (18e-).

16 e- electrons 18 e- A –ion is always larger than the atom.
2–8–6 electron 2–8–8 2-
configurations S is larger than S atom.

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