Exam 1 Flashcards
Matter
anything that has mass and takes up space
gas
no fixed volume or shape
properties of gas
- molecules are far apart and under go frequent collisions
- since they are moving so fast and random they can collide (there’s also a lot of them)
- if compressed in a fixed space more collisions happen
liquid
fixed volume (independent of its container), no fixed shape
properties of liquid
molecules are closely packed (linked with bonds) and move rapidly
solid
fixed shape and fixed volume
properties of solid
- molecules tightly held together
- reason for the fixed shape
Pure substances
have unique composition and does not vary from sample to sample; composition is constant (if the composition is not constant then it is not pure)
Elements
Pure substances that cannot be broken down into simpler parts; make of only one type of atom (basic structure)
molecule
the combination of two atoms
Compounds
- pure substances made of two or more elements or atoms
- Water (H2O), carbon dioxide (CO2)
- definite composition
definite composition
- CO2 here and CO2 somewhere else has the same composition; relative number of atoms of each element in the compound is the same in any sample
- Law of Constant Composition
Homogeneous mixtures
- uniformly mixed on an atomic or molecular level
- same things in one bite
Heterogeneous mixtures
- not uniformly mixed on an atomic or molecular level
- ex: distribution of toppings on pizza; the same things not guaranteed with each bite
Methods to Separate Mixtures
Filtration, Distillation, Chromatography
Filtration
- separating a solid component from the liquid component
- probably with filter paper
Distillation
- separating liquids based on the boiling point of the liquid
- the liquid with the lowest boiling point will boil first
- will vaporize and leave into the condenser
- collect the vapor
Chromatography
- mixture is put on top of the stationary phase (solid/sand-like)
- solvent is added on top (liquid)
- will push the mixture through the stationary phase
- come out as drops
different components will hold on to the stationary phase with a different strengths (chromatography)
- tight hold - come out last
- lose hold - come out first
different components will hold on to the stationary phase with a different strengths (chromatography)
- tight hold - come out last
- lose hold - come out first
Physical Properties
- can be observed without changing the identity or composition of the substance
- ex: color, melting point, density, or conductivity
Chemical Properties
- describes how a substance change or reacts to form other substances
- reaction based
