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Ch. 4 NOTES ~ Formation of Compounds
NOTE: Vocabulary terms are in boldface and underlined. Supporting details are in italics.
I. Element Review
THE SEVEN DIATOMIC MOLECULES (“Super Seven”):
H2 F2 O2 N2 Cl2 Br2 I2
THE METALLOIDS: B, Si, Ge, As, Sb, Te, Po, At
COMMON ELEMENTS TO KNOW (symbols and names):
Ag, Al, Ar, As, Au, B, Ba, Be, Bi, Br, C, Ca, Cl, Co, Cr, Cs, Cu, F, Fe, Fr, H,
He, Hg, I, K, Kr, Li, Mg, Mn, N, Na, Ne, Ni, O, P, Pb, Ra, Rb, S, Sb, Si, Sr,
Sn, U, W, Zn
II. Valence Electron Review
A. Valence electrons—the electrons in the highest energy level of at atom (“highest
shell” or highest n)
1) tells how many are available for bonding
2) tells how many e- will be gained or lost in forming ions
GROUP #: VALENCE # USUALLY, WHEN FORMING IONS:
OUT OF 8:
Group IA 1 loses 1
Group IIA 2 loses 2
Group IIIA 3 loses 3
Group IVA 4 can lose or gain
Group VA 5 gains 3
Group VIA 6 gains 2
Group VIIA 7 gains 1
Group VIIIA 8 does not form ions
B. Review electron dot diagrams (Lewis structures)
III. Atoms and Ions
A. atomic neutrality: atoms are neutral (net charge of zero) # protons = # electrons
B. ion—a charged atom(s) or a charged group of atoms
1) formed by gain or loss of electrons
2) cation— a positive ion formed by losing electrons
3) anion— a negative ion formed by gaining electrons
• common ending is —IDE (chloride, bromide, iodide...)
• ions of Group VIIA, the halogens, are called halide ions
CP AN Cations Positive, Anions Negative “Cat People Are Nice”
YOU CAN’T LOSE OR GAIN PROTONS TO FORM AN ION !
4) an ion has different properties than its element (Na atom vs. Na+ ion)
5) examples...
Q: Aluminum loses three electrons when its ion is formed. Write its symbol and charge. A: Al3+
Q: Oxygen gains two electrons when its ion is formed. Write its symbol and charge. A: O2-
