Transcript Chemistry Notes

Chemistry Notes
Lindstrom 2010
Elements
ELEMENTS
• Atomic number: number of protons in an atom's
nucleus; is unique for each element
• Atomic mass: the weight of protons + neutrons
• How to find neutrons: atomic mass - atomic number
• Location of particles: protons + neutrons = nucleus
electrons = rotate around nucleus
• Charges:
Protons
Positive +
Neutrons
no charge 0
Electrons
Negative -
• If you change the number of
the element name.
protons , you change
• Isotope: one of several forms of an element, each
containing the same number of protons in their atoms
but a different number of neutrons
• Ions: atom that has become electrically charged as a
result of gaining or losing an electron
PHASES
• Solid: state of matter where particles arranged into a
definite shape and volume.
Examples: a brick, a penny, a piece of wood, a chunk of
aluminum metal
• Liquid: states of matter where particles are free to flow,
have a definite volume, but no definite shape.
Examples at room temp: water, mercury, vegetable oil,
ethanol
• Gas: state of matter where particles do not have a
defined volume nor defined shape.
Examples: air, chlorine at room temperature, ozone
• Melting Point:
changing from solid into liquid or
liquid into solid
• Boiling Point:
temperature at which the vapor pressure of a liquid =
pressure surrounding the liquid (depends on
atmospheric pressure)
• Freezing Point:
temperature when liquid changes
to a solid
• Altitude: The altitude of a location is its vertical distance above
sea level
This is a low
altitude situation
This is a high
altitude situation!
• Boiling point is lower at high altitudes- it is faster to boil a pot of
water on a mountain than at the Jersey Shore
• BUT it takes longer to cook food- why?
• Frozen pipes: will burst if water is trapped inside
them and freezes. This is because water
expands when it changes from liquid to solid.
PHYSICAL CHANGE
•
Describe:
A physical change does not produce a new substance.
Changes in phase (melting, freezing, vaporization,
condensation, sublimation) are physical changes.
•
3 examples:
crushing a can
melting an ice cube
breaking a glass bottle
CHEMICAL CHANGE
•
Describe
Chemical changes take place on the molecular level. A
chemical change produces a new substance.
2. 3 examples:
combustion (burning)
cooking an egg
rusting of an iron pan