CHEM 102 Exam 1

Matter

anything occupying space and having mass

Simplest Form of Matter

debatable

Atom

neutrons + protons + electrons
\[ nucleus ]

Element

collection of atoms (same type)

different atoms have different types of atoms

Example of an Element

anything on the periodic table

Compound

combine two or more different elements by forming chemical bonds

have constant composition

Example of a Compound

H2O

Mixture

combination of two or more elements or compounds

Homogeneous Mixture

combination is the same throughout

called solutions, not visibly distinguishable parts

Example of Homogeneous Mixture

air

Heterogeneous Mixture

composition is not uniform

has visibly distinguishable parts

separate mixtures by physical change

Example of Heterogeneous Mixture

trail mix

Physical Change

doesn't change formula of compounds/elements; usually changes the state (gas⇆liquid⇆solid)

Example of Physical Change

melting

Chemical Change

Separating (breakdown) compounds into elements by making or breaking chemical bonds

Example of Chemical Change

burning

Hypothesis

Possible explanation for an observation

Test hypothesis through experiment

Theory

Set of hypothesis that explains some natural phenomenon

often called models

explains why

Law

one statement summarizing what happens

can be a mathematical equation

Example of a law

Ideal Gas Law

PV\=nRT

Qualitative Observation

general observations not requiring a number

Example of qualitative data

Colors, textures, smells, tastes, appearance, beauty, reactivity, state, etc.

Quantitative Observation

observation requiring a number and unit

a measurement

example of quantitative observation

How long, heavy, etc

Scientific Method

observations, hypothesis, experiment, theory

exa

10^18 (E)

peta

10^15 (P)

tera

10^12 (T)

giga

10^9 (G)

mega

10^6 (M)

kilo

10^3 (k)

hecto

10^2 (h)

deka

10^1 (da)

deci

10^-1 (d)

centi

10^-2 (c)

mili

10^-3 (m)

micro

10^-6 (miu)

nano

10^-9 (n)

pico

10^-12 (p)

femto

10^-15 (f)

atto

10^-18 (a)

uncertainty

all measurements have uncertainty

assume +/- 1 in last digit

precision

closeness of a measurement to each other

reproducibility

accuracy

closeness of a measurement to accepter, or true value

SigFig rules for counting

nonzero integers and captive zeros - significant

zeros on left - not significant

zeros on right - significant only if theres a decimal

exact numbers - infinite significant figures

SigFig rules for addition/subtraction

same number of decimal places as number with fewest

SigFig rules for multiplication & division

number with fewest SigFigs limits SigFigs in answer

SigFigs when using constants

don't allow them to limit amount of SigFigs

Dimensional Analysis Set Up

(original unit A/1)(unit B/unit A)(unit C/unit B)

% error

abs(true result-experimental)/true result x 100

related to accuracy

Dalton's Atomic Theory

1. each element is made up of atoms

2. Atoms of the same element are alike, atoms of different elements are different

3. Compounds are formed when atoms of 2 or more elements combine. (a given compound always have the same composition)

4. Law of Conservation of Mass: during chemical reaction, atoms are rearranged, not created or destroyed

Atomic Structure: JJ Thomson

cathose ray rube experiments

beam deflected by magnet (particles are charged)

current moves a paddlewheel (particles have mass)

Conclusion: a negatively charged particle is one of the fundamental particles of the atom

Atomic Structure: Rutherford

gold foil and alpha particle experiment

most went straight through (atom mostly empty space)

some were deflected slightly (protons in nucleus (+) repel the alpha particles (+))

a few bounced back (very dense nucleus)

nuclues makes up the \__________, electons make up the \__________

mass; volume

electrons

negative charge
9.10939 x 10^-31 kg

protons

positive charge
1.67265 x 10^-27 kg

neutrons

no charge
1.67495 x 10^-27 kg

Structure of the atom

mostly empty space

tiny nucleus surrounded by orbiting electrons

nucleus contains most of mass (n+p)

Atomic Number (Z)

number of protons (unique)
number of electrons (when neutral)

Mass Number (A)

Number of protons + neutrons

Isotopes

Atoms of the same element that have different numbers of neutrons

Cations

electrons are lost (metals)

Roman numeral indicates charge

Anions

electrons are gained (nonmetals)

root of element name + ide suffix

Periodic Table

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Ionic Bonds

cations/anions
simplest\= metal + nonmetal
metal in a compound
gaining or lossing electrons

Covalent Bonds

nonmetal + nonmetal
sharing electrons

H2O

water (neutral)

NH3

Ammonia (neutral)

C6H12O6

glucose (neutral)

HClO4

perchloric acid (neutral)

Hg2

Mercury (I) 2+

NH4+

Ammonium +1

NO2

Nitrite -1

NO3

Nitrate -1

SO3

Sulfite -2

SO4

Sulfate -2

HSO4

hydrogen sulfate (bisulfate) -1

OH

Hydroxide -1

CN

Cyanide -1

PO4

Phosphate -3

HPO4

Hydrogen Phosphate -2

H2PO4

dihydrogen phosphate -1

NCS or SCN

Thiocyanate -1

CO3

Carbonate -2

HCO3

hydrogen carbonate (bicarbonate) -1

ClO or OCl

Hypochlorite -1

ClO2

Chlorite -1

ClO3

Chlorate -1

ClO4

Perchlorate -1

C2H3O2

Acetate -1

MnO4

Permanganate -1

Cr2O7

Dichromate -2

CrO4

Chromate -2

O2

Peroxide -2

C2O4

Oxalate -2

S2O3 2-

Thiosulfate -2

HF

hydrofluoric acid

HCl

hydrochloric acid

HBr

hydrobromic acid

HI

hydroiodic acid