Gen Chem 1: Chapter 1: Matter & Measurement

Scientific Method

hypothesis

tentative explanation of an observation or experimental result

theory

tested explanation of an observation or experimental result

law

describes/predicts what will happen

does NOT explain why it happens

laws _____ behavior. theories ____ behavior

laws DESCRIBE behavior. theories EXPLAIN behavior

matter

anything that has mass and takes up space (volume)

atoms

fundamental unit of matter; smallest part of an element that retains that element’s identity

molecules

groups of atoms that are bind tightly together, and behave as a single unit

Matter Chart

pure substances

one type of element or compound; bound to a fixed ratio

elements vs. compounds

elements- one type of atom

compounds- different types of atoms bound together

ionic vs. covalent compounds

ionic cmpd- when atoms exchange electrons to create charged ions (Metal(+) + Nonmetal(-))

covalent cmpd- when atoms share pairs of electrons

molecular compound is a combination of ___ + ____

Nonmetal (-) + Nonmetal (-)

mixtures

more than one substance

homogenous vs. heterogenous mixtures

homogenous- components are evenly blended (ex: salt water)

heterogenous- components are NOT evenly blended (ex: sand and water)

acid

releases a hydrogen ion (cation) (proton)

at 25 degrees C - substance that has pH below 7

solution with HIGH hydronium ion content

most acids are _____ compounds

molecular

6 Strong Acids

1. HCl - hydrochloric acid

2. HBr - hydrobromic acid

3. HI - hydroiodic acid

4. HNO₃ - nitric acid

5. HClO₃ - perchloric acid

6. H₂SO₄ - sulfuric aci

all are molecular cmpds

ionizes completely in water to INC hydronium ion concentration

6 Strong Bases

1. NaOH - sodium hydroxide

2. LiOH - lithium hydroxide

3. KOH - potassium hydroxide

4. Ca(OH)₂ - calcium hydroxide

5. Sr(OH)₂ - stronium hydroxide

6. Ba(OH)₂ - barium hydroxide

stronger acid has the (stronger/weaker), (more/less) stable (more/less reactive) conjugate base

conjugate base differs from the acid by __ ______.

stronger acid has the weaker, more stable (less reactive) conjugate base

conjugate base differs from the acid by one proton

Ex: HCl_(aq) —> H⁺_(aq) + Cl^-_(aq)

the -OH from bases is called the ____ ____; is it nonmetal or metal

hydroxyl group; nonmetal

when the hydroxyl group bonds with a metal, it forms a ____ compound

ionic (ex: NaOH)

when the hydroxyl group bonds with a nonmetal, it forms a ____ compound

molecular (ex: methanol - CH₃OH)

states of matter and each of their relationship to shape + volume

solids: have definite shape and volume

liquids: have definite volume; takes shape of container

gases: NO definite shape NOR volume

Phase Transitions

melting: solid to liquid

boiling (vaporization): liquid to gas

freezing: liquid to solid

condensation: gas to liquid

sublimation: solid to gas

deposition: gas to solid

physical properties vs. physical changes

physical properties: characteristics that we measure WITHOUT changing the substance’s identity

physical changes: changes that occur WITHOUT a change in the substance’s identity (phase transitions like solid to liquid)

chemical properties vs. chemical changes/reactions

chemical properties: characteristics that CANNOT be measured or observed WITHOUT a change in identity

chemical changes/reactions: changes that involve a change in identity; always involves formation of a different substance

energy

ability to do work

2 types of energy

potential energy: stored energy

kinetic energy: energy in motion

what 3 components play a role in potential energy

mass, gravity, height (so bigger hill will have more PE than smaller hill)

exothermic vs. endothermic processes

exothermic: give off heat

endothermic: absorb heat

in an exothermic reaction, is there more energy in reactants or products

REACTANTS have MORE energy (negative enthalpy)

Ex: Carbon + Oxygen —> Carbon Dioxide + Heat

in an endothermic reaction, is there more energy in reactants or products

PRODUCTS have MORE energy (pos enthalpy)

Ex: Water + Heat = Steam

mass

length

time

temperature

light intensity

electric current

chemical amount

mass —> kilogram (kg)

length —> meter (m)

time —> second (s)

temperature —> Kelvin (K)

light intensity —> candela (cd)

electric current —> ampere (A)

chemical amount —> mole (mol)

tera-

gigga-

mega-

kilo

hecto-

deka-

unit

deci-

centi-

micro

nano-

pico

T - 10¹²

G - 10⁹

M - 10⁶

k - 10³

h - 10²

da- 10¹

10⁰

d 10^-1

c - 10^-2

m - 10^-3

μ - 10^-6

n - 10^-9

p - 10^-12

freezing point in ℉, ℃, K

℉ - 32 ℉

℃ - 0 ℃

K - 273.15 K

intensive vs. extensive properties

intensive properties: independent on the amount of matter present (color, temperature, density, hardness)

extensive property: depends on the amount of matter present (mass, volume, length, total energy, number of moles)

accuracy vs. precision

accuracy: how close the measured value is to the actual value

precision: closeness of a set of measurements

determine number of sig figs

1. 4,908

2. 5.00

3. 1.0230

4. 0.045

5. 1,830

6. 1.830 × 10³

1. 4

2. 3

3. 5

4. 2

5. ambiguous

6. 4

Sig Figs in Multiplication & Division vs. Addition & Subtraction

Mul & Div - report same number of digits as are in the measurement with the fewest significant digits

Add & Sub - report answer with the same number of digits after the decimal as there are in the measurement with the fewest digits after the decimal

Sig Fig Rules for Logarithms

report same number of decimal places as the number of sig figs in the mantissa

ex: log⁡(3.70×10^−7)=−6.432

Because 3.70×10^−7 has three significant figures, −6.432 has three digits after the decimal point.

speed =

time =

speed = distance/time

time = 1/speed

a chemical reaction that releases energy (an ——— reaction) results in ———(products/reactants) that are thermodynamically more stable

exothermic reaction

products more stable

When writing in scientific notation, the leading numbers must be between ___ and ___

1 and 10

ex: 617 will be 6.17 × 10²

for scientific notation,

when moving the decimal point to the LEFT, the exponent will be (i/pos)

when moving the decimal point to the RIGHT, the exponent will be (neg/pos)

moving decimal point to LEFT - POS

moving decimal point to RIGHT - NEG

burning candle - identify the different energies in the

flame

wax

flame: thermal energy & energy as light

wax: potential energy & chemical energy (energy stored between bonds of atoms)x

density of water = _____ g/mL

objects LESS dense than water (float/sink)

objects MORE dense than water (float/sink)

density of water = 1 g/mL

objects LESS dense than water (float)

objects MORE dense than water (sink)

ammonium (NH₄⁺) behaves as a (nonmetal/metal)

metal

polyatomic cations usually bond with _____ (metal/nonmetal) to form a(n) _____ compound

nonmetal; ionic compound

ex: NH₄⁺

polyatomic anions usually bond with _______ (metal/nonmetal) to form a(n) ____ compound

metal; ionic compound