Chemistry 2 a, b, c
Biological, chemical, and physical
properties of matter result from the
ability of atoms to form bonds from
electrostatic forces between electrons
and protons and between atoms and
molecules. As a basis for understanding
this concept:
IONIC bonds
Chemical bonding formed through
electrostatic attraction between two
oppositely charged ions. Ionic bonds are
formed between a metal and a nonmetal
ion.
COVALENT bonds
Chemical bonding that is characterized by
the sharing of pairs of electrons between
atoms, and other covalent bonds. In
short, the stable balance of attractive and
repulsive forces between atoms when
they share electrons
Last First
Period Date
METALLIC bonds
Electromagnetic interaction between
delocalized electrons, called conduction
electrons, gathered in an "electron sea",
and the metallic nuclei within metals.
CH 2. a. Students know atoms combine to
form molecules by sharing electrons to
form covalent or metallic bonds or by
exchanging electrons to form ionic bonds.
CH 2. b. Students know chemical bonds
between atoms in molecules such as H2, CH4,
NH3, H2CCH2, N2, Cl2, and many large
biological molecules are covalent.
What is the difference between an ionic and a
molecular compound?
2 H2(g) + O2(g) → 2 H2O(l) + 572 kJ (286 kJ/mol)
Ionic compounds are between metals and nonmetals.
Molecular (covalent) compounds are between only
non-metals.
(Metallic compounds are between metals and other
metals)
An ionic compound is a pure substance that is
formed from a metal and a nonmetal. It has a fairly
high melting point and is a conductor of electricity
when in a molten or aqueous state.
A molecular compound, on the other hand, is a pure
substance that is formed from nonmetals. It has a
fairly low melting point, and cannot conduct
electricity regardless of state. Another important
difference between the two is that an ionic
compound is a crystalline solid at standard
temperature and pressure (STP), whereas a
molecular compound can be in a solid, gas or liquid
state at STP.
CH 2. c. Students know salt crystals, such
as NaCl, are repeating patterns of positive
and negative ions held together by
electrostatic attraction.
Chloride and sodium ions, the two major
components of salt, are needed by all known
living creatures in small quantities. Salt is
CH4 + O2 → CO + H2 + H2O
involved in regulating the water content
(fluid balance) of the body. However, too
2 NH4Cl + 2 CaO → CaCl2 + Ca(OH)2 + 2
much salt increases the risk of health
NH3
problems, including high blood pressure.
H2CCH2
This compound is the simplest form of an
alkene (a hydrocarbon that contains a carbon carbon double bond) called ethene or ethylene
6 Li + N2 → 2 Li3N
3 Mg + N2 → Mg3N2
Cl2 + H2O
HCl + HClO