density

MASS AND DENSITY DIRECTLY RELATED

VOLUME AND DENSITY ARE INVERSELY RELATED

• heating causes object to expand, increasing volume, and thus decreasing mass

• more dense objects will sink

what is chemistry?

• science that seeks to understand what matter does by studying what atoms and molecules do

• discover relationships between particle structure of matter and the properties of matter we observe

• CENTRAL SCIENCE

what is matter

anything that takes up space (occupies volume) and has mass

• TAKES UP SPACE/OCCUPIES VOLUME

• HAS MASS

• smooth and continous

• made up of ATOMS - what make up elements and MOLECULES - what make up compounds (which are made up of 2+ atoms)

HOW MATTER IS CLASSIFIED:

1. Pure substrance: unfirom material of definite composition with characteristic properties

2. same physical and chemical properties

3. display constant composition; HOMOGENUS

4. separation by chemical properties

5. temperatures remain constant during phase changes

PURSE SUBSTANCE TWO SUBCATEGORIES

1. ELEMENTS (smallest pieces)

2. COMPOUNDS (2 or more diff elements)

MIXTURES: has variable compostion parts are separated by physical means

1. homogenous

2. heterogenous

Phases of Matter

1. Solids

   1. can be crystalline (longe range repeating order) or amorphouse (random)

   2. FIXED SHAPE

   3. DEFINITE VOLUME

   4. NOTE COMPRESSIBLE

   5. DO NOT FLOW

2. Liquids

   1. definite volume but rates shape of containe

   2. INDEFINITE SHAPE

   3. DEFINITE VOLUME

   4. NOT COMPRESSIBLE

   5. CAN FLOW

3. Gas

   1. INDEFINITE SHAPE

   2. INDEFINITE VOLUME - TAKES SHAPE OF CONTAINER

   3. COMPRESSIBLE - CAN BE PACKED INTO TIGHTER SPACE

   4. CAN FLOW

sublimation solid to gas

gas to solid deposition

freezing, melting

vaporationz, condensation

Proprties and changes of matter

physical properties: can be changed without changing compostion, directly observable

• Intensive properties (e.g., density, temperature, boiling point) are independent of the amount of substance present, often used to identify materials. Extensive properties (e.g., mass, volume, energy) depend on the total amount of matter, scaling with system size. Intensive properties are non-additive; extensive properties are additive

physical changes and separation techniques

alters the overall appearance but not the actual compostion of matter, not whats it made of

1. CHROMATOGRAPHY based on adherence to surface

2. EVAPORATION HOMOGENEOUS liquid removed from solid (water boil, salt)

3. DISTILLATION based on volatilty-boiling points of two liquids evenly mixed together a physical separation technique used to purify liquids or separate mixtures based on differences in their boiling points (volatilities)

4. FILTRATION - HETEROGENEOUS MIXTURES: insoluble solid is removed from a liquid (and vice versa)

what is energy?

• the ABILITY TO DO WORK

• ABILITY TO CAUSE CHANGE

1. potential

2. kinetic

heat thermal energy: kinetic of particles

• physical: energy is transfered as part of phase changes

• chemical: added or released

endothermic: absorb heat energy as changes

exothermic: release heat energy as changes