chem honors ch 1-2

intro, matter, energy

matter

matter

everything that has mass (all physical objects)

macroscopic

visible to the naked eye

microscopic

seen with a microscope

particulate

cannot be directly seen (the particles that make up matter)

macro, micro, and particulate behavior of matter

knowing how to control particles allows you to also control macro or micro behaviors

model

in chemistry:

representation of particulate-sized matter (atoms, molecules)

ball-and-stick model

shows atoms as balls and linking electrons as sticks

space-filling model

shows the outer boundaries of a particle (3D)

Kinetic Molecular Theory

all matters consists of (extremely tiny) particles that are in constant motion

*kinetic = motion, molecular = molecule

heat + states of matter

increases particle speed

molecules are _________ to one another

attracted

gas

fast-moving molecules, that can overcome attractive forces (don’t touch/far apart)

gas shape & volume

shape - same as closed container

volume - same as closed container

liquid

slower moving molecules, that touch one another but can still move freely amongst themselves

liquid shape and volume

shape - same as container (bottom bc of gravity)

volume - constant/fixed

solid

molecules stuck together in fixed positions, can only vibrate or shake

solid shape and volume

shape - constant/fixed

volume - constant/fixed

crystalline solid

molecules are fixed and arranged in a pattern (ex. table salt, snowflakes)

amorphous solid

molecules are fixed but with no pattern (ex. rubber, types of plastic/glass)

physical properties

characteristics observed and recorded without altering the substance’s identity (ex: color, density, hardness, boiling point)

physical change

change in the form of a substance without changing its chemical identity (ex. size, shape, phase/state change)

chemical change

when the chemical identity of a substance is destroyed, and a new substance forms (aka chemical reaction)

• (ex. breaking the bonds in water to create hydrogen gas and oxygen gas)

chemical properties

all the possible chemical changes/reactions of a substance (how a substance reacts with other substances or energy)

• (ex. water turns into H and O when exposed to an electric current)

chemical change indicator examples

change in color, release of heat or light (exothermic reaction), gas formation

pure substance

substance made up of a single chemical (one type of molecule)

• own set of physical and chemical properties

• identity doesn’t change from physical change

mixture

sample of matter made of two or more pure substances mixed together

• properties of mixture depend on substances in it

homogenous

a mixture that is uniform in appearance and composition throughout (also called a solution)

*a pure substance is also homogenous

phase

the different separate, distinct layers forming a heterogeneous mixture (ex. oil and water layers)

heterogenous

a mixture with different phases visible to the naked eye

distillation

uses physical change (evaporation and condensation) to separate part of a mixture (typically water)

filtration

using the physical properties of a mixture to separate components (ex. separating different phases created by density)

element

cannot be decomposed or separated chemically into stable pure substances (or just different substances in general)

compound

can be decomposed by chemical change into other pure substances (ex. H20)

chemical formula

symbols representing the atoms that make up a compound (ex: Na, H20)

atom

smallest particle of an element

molecule

smallest unit particle of a pure substance (can be an element or compound)

Law of Constant Composition

“Any compound is always made up of elements in the same proportion by mass”

• the mass of a compound equals the mass of its elements in their set proportions

• (basically saying mass a + b = c)

static electricity (electrostatic force)

forces of attraction or repulsion between electrically charged objects

Energy

ability to do work or transfer heat

exothermic vs endothermic

exothermic (out) - chem change that transfers energy into surroundings

endothermic (in) - chem change that removes energy from surroundings

kinetic vs potential energy

kinetic - energy due to the motion of an object

potential - energy possible/stored through the particle’s arrangement or position (ex. sucrose for plants or gravitational potential energy)

Laws of Conservation (3 of them)

Mass and Energy - total quantity of mass and energy in universe is fixed (does not change)

Mass - total mass of reactants in a chemical change = total mass of products

Energy - quantity of energy within an isolated system does not change