Matter & Energy 10/17

Physical property

a characteristic of matter that can be observed without altering (or intending to alter) the sample’s composition. INTENSIVE OR EXTENSIVE

Chemical property

a characteristic that describes how a substance interacts with other substances; it must be observed by changing (or attempting to change) a sample’s composition. ALL INTENSIVE

Intensive property

a property that does not depend on the amount of matter in a sample. (ex: boiling pt, magnetism, pH, malleability, color, ductility, temp, conductivity, density, specific heat.)

Extensive property

a property that does depend on the amount of matter in a sample. (ex: mass, volume, dimensions [w, l, h], weight, # of particles, heat energy.)

Physical change

a change that alters physical properties but does not alter a substance’s composition. (ex: evap/phase changes, cutting, grinding, any physical deformation.)

Chemical change

a change that affects a substance’s composition by creating new substances. (ex: combustion, rusting, grilling, baking, fermenting, digestion, mold, photosynthesis.)

Matter

• takes up space

• cannot be created nor destroyed

• has mass

Pure substance

• one type of PARTICLE

• constant composition

• cannot be broken down by physical means

• no visible boundaries

Element

• one type of ATOM

  • defined by # of protons

Compound

• 2+ types of atoms

• chemically bonded

• no visible boundaries

Can be separated by chemical changes.

Allotropes

Different structural forms of the same element. (ex: oxygen - O₂ gas, O₃ ozone. Carbon - graphite and diamond)

Isomers

• same % composition but different structure

  • different properties

• “C₂H₆O”

  • CH₃CH₂OH - ethanol

  • CH₃OCH₃ - dimethyl ether

Mixture

• variable composition

  • “salt water”

• 2+ substances

• no covalent (shared-valence) bonds

Can be separated by physical changes; even by hand.

Heterogeneous mixtures

• visible boundaries

  • cutoff=microscope

• most foods

• ex: minerals, like granite

Homogeneous mixtures (Solution)

• uniform appearance

• no visible boundaries

• ex: air

Alloy (Solution)

• mixture of 2+ metals

• ex. brass, bronze, steel, pewter, solder, amalgam

Colloid

• stable

• NOT a solution

• ranges from translucent → opaque

• medium-sized particles

• ex: milk, paint, mayo

Suspension

• unstable, settling mixture

• has largest particles

• opaque

• ex: vinaigrette, pulp/OJ, dirt water

Solute

is the substance being dissolved

Solvent

is the dissolving substance/medium

Filtrate

the liquid produced after filtration process

Residue

the substance(s) remaining after the separation

Equilibrium

the equal exchange of rates

Boiling

Conversion of a liquid to a vapor within the liquid as well as at its surface. Occurs when the equilibrium vapor pressure of the liquid equals the atmospheric pressure.

Volatile

• has a relatively low BP

• has a relatively high vapor pressure

• weak IMFs

• steeply-sloped graph

• volatility rises as temp rises

Entropy

describes level of disorder in a system.

Enthalpy

Total heat content (heat energy) of a total system at constant pressure.

Latent heat

The amount of heat energy absorbed or released by a substance during a phase change without a change in temperature.

Fusion

Solid→liquid

Vaporization

Liquid→gas

Sublimination

Solid→gas

Freezing

Liquid→solid

Condensation

Gas→liquid

Deposition

Gas→solid