chem

things i need to remember

observation

qualitative data: info that describes color, odor, shape, or other physical characteristics

quantitative data: numerical info such as temperature or pressure

hypothesis

tentative, testable statement or prediction about an observation

experiment

set of controlled observations that test the hypothesis

• independent: what you plan to change in your experiment

• dependent: changes based on independent variable

• control: a standard for comparison; consistent across experiment

conclusion

a statement based on experimental measurements and observations

• includes a summary of the results, whether or not the hypothesis was supported, the significance of the study and future research

theory

explanation of a natural phenomenon based on observations and investigations over time

• not the same as a hypothesis

models for the way nature is and tries to not only explain what nature does but WHY

law

a relationship in nature that is support by many explanations

• generalizations of what nature does

• patterns

precision

reproducibility

check by repeating measurements

poor precision results from poor techniques

accuracy

correctness

check by using a different method

poor accuracy results from procedural or equipment flaws

solid

definite volume, definite shape, very rigid, closely packed molecules

liquid

definite volume, definite shape, less rigid and can flow, weakly packed molecules

gas

indefinite volume, indefinite shape, no rigidity and flows easily, poorly packed molecules

physical properties

a characteristic that can be observed or measured without changing the identity of the substance

• often used to describe a substance

• melting point, boiling point, density

a change in a substance that does not involve a change in the identity of the substance

• grinding, cutting, melting, and boiling

chemical properties

relates to a substance’s ability to undergo changes that transform it into different substances

• acidity, flammability, toxicity

a change in which one or more substances are converted into different substances

• combustion, cooking food, rusting metal

metals

solid at room temperature (except for mercury)

reflective surface

good conductors of heat and electricity

malleable

ductile

lose electrons to form cations

nonmetals

occupy the right side of the periodic table (except for hydrogen)

generally gases or brittle, dull solids (except bromine)

poor conductors of heat and electricity

group 17 - halogens

group 18 - noble gases

tend to gain electrons to form anions

metalloids

also known as semimetals

have physical and chemical properties of both metals and nonmetals

• includes boron, silicon, germanium, arsenic, antimony, and tellurium

alkali metals

group 1 mentals (except hydrogen)

soft, low melting point, low density

alkaline earth metals

group 2

harder, higher melting points, and denser than alkali metals

reactive, but less than corresponding alkali metal

form stable, insoluble oxides form which they are normally extracted

oxides are basic = alkaline earth

halogens

group 17

nonmetals

diatomic elements (F₂, Cl₂, Br₂, I₂)

react with metals to from ionic compounds

noble gases

gases at room temperature

very low melting and boiling points

unreactive, chemically inert

Al

aluminium

Ar

argon

Ba

barium

Be

beryllium

B

boron

Br

bromine

Ca

calcium

C

carbon

Cl

chlorine

Cr

chromium

Co

cobalt

Cu

copper

F

fluorine

Au

gold

He

helium

H

hydrogen

I

iodine

Fe

iron

Pb

lead

Li

lithium

Mg

magnesium

Mn

maganese

Hg

mercury

Ne

neon

Ni

nickel

N

nitrogen

O

oxygen

P

phosphorus

Pt

platinum

K

potassium

Sc

scandium

Si

silicon

Ag

silver

Na

sodium

S

sulfur

Ti

titanium

U

uranium

V

vanadium

Zn

zinc

acetate

C₂H₃O₂^-

acetate

CH₃COO^-

acetate

CH₃CO₂^-

ammonium

NH₄⁺

carbonate

CO₃^2-

bicarbonate

HCO₃^-

perchlorate

ClO₄^-

chlorate

ClO₃^-

chlorite

ClO₂^-

hypochlorite

ClO^-

phosphate

PO₄^3-

cyanide

CN^-

hydroxide

OH^-

sulfate

SO₄^2-

sulfite

SO₃^2-

bisulfate

HSO₄^-

bisulfite

HSO₃^-

permaganate

MnO₄^-

mercury(I)

Hg₂²⁺

nitrate

NO₃^-

nitrite

NO₂^-

chromate

CrO₄^2-

dichromate

Cr₂O₇^2-

thiocyanate

SCN^-

hydrochloric acid

HCl (aq)

hydrobromic acid

HBr (aq)

hydroiodic acid

HI (aq)

perchloric acid

HClO₄ (aq)

nitric acid

HNO₃ (aq)

sulfuric acid

H₂SO₄ (aq)