Chemistry Unit 1

Chemistry

study of the structure and changes of matter

mass

amount of matter in a substance

matter

anything that has mass and occupies space

Energy

ability to do work (work=applying a force)

Potential energy

energy of position or due to circumstances

ex. raising a book up, a rollercoaster sitting on the top of the drop

kinetic energy

the energy of motion

ex. rollercoaster going down a drop

Radiative energy

light

5 branches of chemistry

organic chemistry

inorganic chemistry

physical chemistry

analytical chemistry

biochemistry

branches can overlap!

organic chemistry

study of most carbon compounds except oxides, carbonates, and biocarbonates

Inorganic chemistry

study of most matter that doesn’t contain carbon

Physical chemistry

the study of behavior and changes in matter and energy changes

analytical chemistry

study of composition of matter both qualitatively and quantitatively

Biochemistry

study of molecules of living organisms (subset of organic chemistry)

Scientific method

1. Oberservation

2. Hypothesis

3. Experiment

4. Theory or Model/Law

Observation

a use of the senses directly/indirectly to obtain information about the system being studied

qualitative or quantitative

Qualitative vs Quantitative

Qualitative: descriptive/compative, ex. A is red

Quantitative: Numerical, includes a unit, X occupies 15 mL

Property(trait/characteristic of matter) isn’t qual or quant but the expression is ex. observing an object’s temperature saying it’s hot/ 95 C

Scientific Notation

left= postitive

right= negative

Derived properties

combination of one or more of the fundamental properties (Mass, length, time, temperature, amount of substance, electrical current, luminous intensity)

ex. area, volume, density

Mass vs Weight

Mass is the amount of matter

Weight is the force due to gravity exerted on mass

you will not have the same weight on the moon but you will have same mass

heat vs temperature

temperature determines direction of heat flow bw 2 bodies in thermal contact

heat: flows spontaneously from the hotter body to the colder body

Defenition

explain WHAT something is, providing clarity for terms and concepts.

Law

say what will happen, based on evidence

Theory

an explanation supported by repeated experimentation, answer How/Why?, can be represented using a model

Area

how large a surface is (m²)

Volume

amount of space occupied (m³), (mL) = 1 cm³ = 10^-6 m³, (L) = 1 dm³ = 10^-3 m³

Density

mass/volume, kg/m³, g/cm³ = g/mL, dense objects sink, more dense objects sink in less dense fluids

Specific gravity

ratio of an object’s density to that of water

Accuracy vs. Precision

Accuracy: how close an experimental result is to true/accepted value, shown for 1 value or an average

Precision: reproducibility, best shown using statistics on multiple measurements

Absolute error

way to represent accuracy

experimental value - accepted value

Percent error

way to measure accuracy

experiemental value - accepted value/ accepted value x 100%

(+)= experiemental value larger than accepted

(-)= experimental value smaller than accepted

Significant Figures

representation of precision

digits in a measurements for which an actual measurement was made

Recording a measurment

record every certain digit and one uncertain digit

ex. reading a thermometer and the line is in between 13 C and 14 C record measurement of 13.5 C

Rules for Identifying Sig Figs

1. All nonzero digits are significant (the numbers not in 10 of scientific notation are significant), ex. 3.25 kg is 3 sig figs

2. Zeroes between sig figs are significant, ex. 30.05 kg is 4 sig figs

3. Zeros both to the right of the decimal and to the right of the sig figs are significant, ex. .1000 s is 4 sig figs

4. Introductory zeroes before decimal and place-holders are not significant, ex. 0.0300 kg is 3 sig figs

5. Exact numbers, such as definitions and careful counts have unlimited significance since there is no uncertainty

6. When adding or subtracting the result should be rounded to the same number of decimal places as the measurement with the fewest decimal places.

7. The number of significant digits in the result is the least number of sig figs in any of the factors or quotients.

Physical Properties/Changes vs Chemical Properties/Changes

Physical: do not involve changing of material identity, size, shape, volume, mass temperature, color, density, solubility in water, boiling/melting points, change of state, dissolving and crystallizing, breaking into smaller pieces, change of temperature

Chemical: do involve changing on material identity, baking soda reacting with vinegar to produce carbon dioxide, acids reacting with bases, unexpected production of a new phase, strong release/absorption of energy such as heat/light, drastic change in color or odor

Extensive vs. Intensive

Extensive: values dependent on mass, volume, size, heat capacity

intensive: values not dependent on mass, color, density, boiling/melting point, temp

Reactant

materials that combine chemically

product

created by change

Matter states

Solid, Liquid, Gas

Solids

tightly closely packed, insufficient kinetic energy to overcome interparticle forces, volume and shape fixed

Liquids

fairly closely packed, kinetic energy to overcome some interparticle forces, volume fixed, shape depends on container

gas

spread far apart, can overcome all interparticile forces w/ kinetic energy, volume and shape depend on container

vaper= gas normally solid or liquid at room temp

Kelvin to Celcius

K to C: 0K − 273.15 = -273.15°C

C to K: 0C+273.15=273.15 K

metric prefixes

mega = 10^6

kilo= 10³

deci = 10^-1

centi= 10^-2

milli= 10^-3

nano= 10^-9

pico= 10^-12

femto= 10^-15

micro (u)= 10^-6

A with a dot measures wavelength

dimensional analysis

make sure to square or cube the conversion factor

ex. dm² to cm²:

10 dm²/1 x (10 cm/ 1 dm)² = 1.80 × 10^4

information on a circle

sharing of electrons across all six carbon bonds within the molecule.

Law of Conservation of Mass

in any ordinary physical or chemical change the total mass stays the same

Substance vs Mixture

Substance: form of matter with constant composition and uniform properties

Subdivisions

Compounds: chemically separable, two or more elements

Element: not chemically separable

Mixtures: composed of two or more substances that are physically combined, variable composition, can be phycially seperated

Subdivisions

Heterogeneous: Variable properties, non-uniform composition, granite, sand in water, sulfur powder, iron fillings

Homogeneous: Uniform properties, Uniform composition, clean air, steel, unsaturated salt water, carbonated water

5 ways of physical seperation

Filtration: seperation of an undissolved SOLID from a LIQUID using a porous barrier

Distillation: using differences in BOILING points

Crystallization: seperation of DISSOLVED solid by EVAPORATION of the LIQUID solvent

Chromatography: based on differences in ADSORPTIVE properties

Law of Definite Proportions

specific compounds always contain elements in the same ratio by mass

Percent by Mass

mass of element/mass of compound x 100%

Phase vs Interphase

phase: any part of a system that is uniform in both properties and composition, ex. homogeneous

Interphase: what seperates two or more phases in heterogenous mixtures