why do atoms form
bonds?
 | Energy:
the capacity to do work |
| Atoms
without the outer most layer of energy will form chemical bonds to become
stable. |
| An input of energy is needed to break chemical bonds between atoms. Energy is released when bonds form between atoms. |
how do ionic and covalent bonds compare?
| Covalent
bonds forms when each of two atoms contributes one electron to a pair, which
the atoms then share. The bond is the electrical pair.
A hydrogen molecule consists of two hydrogen atoms linked by a
covalent bond. The atoms share
the electron pair equally. A
polar covalent bond forms when one atom has a stronger attraction for the
electron pair. This atom gains
a slight negative charge. The
other atom becomes slightly positive. |
| An ionic bond results when one atom loses an electron to form a positive ion, and another atom accepts the electron to form a negative ion. The attraction between the two atoms holds them together. Most ionic compounds, such as table salt, which is also known as sodium chloride, are solids in which the positive and negative ions pack together to form crystals. |
| Monatomic
ion: cation or anion formed from a single atom. |
| Binary
compound: compound composed of two elements |
| Ionic
compounds are named by joining the cation and anion names. |
| The subscripts in the formula for an ionic compound indicates the lowest electrically neutral whole-number ratio of cation to anion. |
what is a polyatiomic ion?
| Polyatomic
ion: ion made of two or more atoms bonded together that function as a single
ion. |
| Parentheses
are used to group polytomic ions in a chemical formula with a subscript. |
| Lewis
structure: diagram showing the arrangement of valence electrons among the
atoms in a molecule. |
|
Prefix |
# Of atoms |
|
o
Mono- |
1 |
|
o
Di- |
2 |
|
o
Tri- |
3 |
|
o
Tetra- |
4 |
|
o
Penta- |
5 |
|
o
Hexa- |
6 |
|
o
Hepta- |
7 |
|
o
Octa- |
8 |
|
o
Nona- |
9 |
how are molecules specified?
| Empirical
formula: simplest whole- number ratio of atoms that matches the relative
ratio found in a chemical compound. |
| Structural
formula: indicates the spatial arrangement of atoms and bonds within a
molecule. |
| The
higher the electronegativity difference, the more ionic the bond character. |
| Intermolecular
forces, such as hydrogen bonds, dipole force, and London forces, link
molecules to each other. |