12/11/08
Post date: Dec 10, 2008 12:2:22 AM
Bell Activity: What holds a compound together?
Chemical bonds
The forces that hold atoms or ions together in a compound
Are a way to store energy
Can be broken and reformed to make new compounds
Chemical structure
Building Structure
The way a building's parts fit together
Can be represented with blueprints
Chemical Structure
The way the compound's atoms are bonded together to make the compound
Can be represented by various models
In pairs, come up with a way to "blueprint" a Carbon dioxide molecule (1 carbon atom and 2 oxygen atoms)
Each pair draws theirs on the board
Other models commonly used
Ball and stick model
Atoms are represented by circles
Bonds are represented by sticks
Makes it easy to see shape of the compound
Bond angle - angle between bonds in a compound
Bond length - the distance between the nucleus of an atom and the nucleus of an atom it is bonded to
Structural formulas
Similar to ball and stick, but use the chemical symbols to represent the atoms
Space-filling model
Shows the relative sizes of atoms in a compound, but not bond lengths
Each example shows a model of water (2 hydrogens and one oxygen) in a different way to present different information
Bonds can bend, stretch, and rotate without breaking.
Atoms are constantly in motion, vibrating and spinning around, but this does not break the bond
We usually show a bond with a solid line, but it really behaves more like a flexible spring
Draw a ball and stick model, structural formula, and space-filling model for each of the following compounds. For the space-filling model, assume that the larger atomic number an atom has, the more space it fills.
Oxygen gas, 02
Carbon dioxide, CO2
Carbon monoxide, CO
Dihydrogen sulfide, H2S
Tin fluoride, SnF2
Sucrose, C6H12O6