Chemistry final review

chapter 2-5

chemistry

the study of matter and the changes it undergoes

matter

anything that takes up space and has mass. basic building block of the universe.

presuppositions

based off belief. The ways people approach their work with different assumptions which are the basis of their worldview.

quantitative data

data in the form of numbers determined through measuring

qualitative data

data in the form of words used to describe something

properties

distinguishing characteristics of matter

physical properties

can be measured or observed without changing the actual composition of the material (ex: color, shape, physical state, density, malleability, ductility, and conductivity)

chemical properties

describes how matter acts in the presence of other materials or how it changes composition when sufficient energy is added to it.

chemical changes

changes in the identity of the material that result in a different material.

physical changes

material changes in state and shape but identity isn’t altered.

pure substances

consists of only one type of matter

mixture

material that can be separated into 2 or more pure substances by physical change.

element

pure substance that cannot be broken down into a simpler substance by ordinary chemical means. consists of only one type of atom.

atoms

basic particles that make up elements

molecules

distinct groups of atoms bonded together

compounds

pure substances that consist of 2 or more elements chemically combined

monoatomic

an element occurs naturally as individual atoms. rare.

diatomic

elements whose atoms naturally bond into pairs

energy

the ability to do work

tempurature

average kinetic energy

thermodynamics

to study the movement and conservation of energy especially thermal energy.

first law of thermodynamics

law of conservation of mass and energy: matter and energy can neither be created or destroyed, only converted from one form to another.

second law of thermodynamics

entropy: all natural processes tend toward the highest entropy and minimum usable energy (all natural systems move toward disorder).

entropy

the measure of dispersal of energy

endothermic

chemical changes that absorb energy

exothermic

chemical changes that release energy

Celsius scale

uses two reference points: the freezing point of pure water is 0 and the boiling point of pure water is 100.

kelvin scale

no negatives. uses absolute zero as 0

third law of thermodynamics

no matter can reach absolute zero (where there is no motion)

Unit

needed to be defined for dimensions. one of something.

measurement

the act of comparing an unknown quantity to a standard unit.

error

our measurements will always be different from the exact precise measurement.

accuracy

how close the measured value is to the accepted value.

precision

how repeatable a measurement is or how exactly one can make a measurement.

Significant digits rules

1. They only apply to measured data
2. all non-zero digits are significant
3. all zeros in between non-zeros are significant
4. decimal points define significant zeros
5. significant zeros in the ones place are followed by a decimal
6. the decimal factor of scientific notation contains inly significant figures.

atom

smallest particle capable of chemical interactions

law of definite composition

every compound is formed of elements combined in specific ratios by mass that are unique for that compound.

Niels Bohr

he suggested electrons exist only in certain energy levels outside of the nucleus.

line spectrum

each element has its own pattern of bright lines

quantum

a fixed sized package of energy

ground state

atom’s lowest energy state

atomic spectra

exact energy locations are different for each type of atom. Like a fingerprint for atoms.

s sublevel

can only hold 2 electrons

p sublevel

can only hold 6 electrons

d sublevel

can only hold 10 electrons

atomic weight/mass

average weight of an element (upper left corner of element)

isotopes

all the possible ways an element can present itself. (neutrons)

cation

positively charged atom

anion

negatively charged atom

groups/family

column on the periodic table. has similar characteristics

period/series

horizontal on periodic table

metalloids

touching the stair line on the periodic table. can act like a metal and non-metal.

atomic radius

distance from the center of an atom’s nucleus to it’s outermost electron.

ionization energy

measures how easily electrons are taken away from atoms to form cations.

electronegativity

the attraction of the nucleus pulling on electrons for the purpose of bonding.

octet rule

atoms want to gain noble gas stability.

covalent bonds

bonds formed by sharing an electron

polarity

difference in electronegativity

diatomics

molecules that bond with themselves

ionic bonds

when an atom with a greater electron affinity takes an electron from another atom and they become ions. metal and non-metal.

metallic bonding

metals bond with other metals within the d orbitals. uses the sea of electrons.

properties of covalent bonds

lower melting point/boiling point, soft and felxible, poor conductors.

properties of ionic bonds

higher melting point/boiling point, hard/brittle, poor conductivity while solid, excellent conductor when liquid.