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Chemical Bonding. Elements are made of only one kind of atom . Example: Cu Al When two or more elements combine chemically, a compound is formed. Example: NaCl H 2 O. Elements. Aluminum Potassium Sulfate. AlK (SO 4 ) 2. Sodium Bicarbonate. NaHCO 3. Zinc Oxide. ZnO.
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Elements are made of only one kind of atom. Example: Cu Al When two or more elements combine chemically, a compound is formed. Example: NaCl H2O
Aluminum Potassium Sulfate AlK(SO4)2
Sodium Bicarbonate NaHCO3
Zinc Oxide ZnO
Cupric Sulfate CuSO4
Atoms use their valence electrons to form bonds. Valence electrons are the electrons in an atom’s last energy level
You can determine valence electrons by determining the group the element belongs to. (Subtract 10 from groups 13 – 18 to determine valence electrons.)
An atom with fewer than 8 valence electrons is more likely to form bonds.
Atoms use the “magic number 8” to make their outer energy levels stable. (Except for H and He. Their “magic number” is 2.)
Atoms of elements in group 18 don’t usually form compounds because they already have 8 valence electrons. (Helium either because its outer energy level only holds two electrons and that’s how many it has.)
form when an atom loses or gains electrons from a nearby atom the oppositely charged ions are attracted to each other
Ionic bonds usually form between a metal and a nonmetal the new compounds formed are called ionic compounds
A covalent bond is formed when atoms share electrons to reach the “magic number 8” in their outer energy level
Covalent bonds usually form between two nonmetals. Covalent compounds are made of individual particles called molecules