Term | Definition |
Chemistry | study of the composition of substances (matter) & the changes they undergo |
Scientific Method | general procedures used in science to problem solve |
4 steps of the scientific method | - observation: questions
- hypothesis: a tentative assumption
- experiment: test
- theory: alter, reject, accepting/summarizes, hypothesis |
Scientific Notation | used to represent vary small or large numbers |
Positive Exponents | - large #'s move decimal to left |
Negative Exponents | - small #'s move decimal to right |
Inexact Numbers | - are obtained through measurements or observation
- contains some uncertainty |
Exact Numbers | are obtained by counting items or from established equivalents |
Accuracy | close to accepted (true) value |
Precision | how close values are to each reproducibility |
Significant Figures | inexact (measured) #'s that have a final digit that is estimated |
In sig figs how do you measure | measure one past the last calibrated mark place values |
uncertainty depends on what when measured | depends on the device used to measure |
sig figs do not apply to | to exact #'s |
english to english or metric to metric are considered | exact numbers |
Specific Gravity | compares the density of a substance to a density of water at 4 degrees celsius |
Density of water equals | 1.00 g/ml |
what is specific gravity's unit | has no units |
what measures specific gravity | hydrometer |
Matter | - anything that exists & takes up space
- natural, synthetic
- classified by components; |
Naturally Occurring | it is isolated from natural resources |
Synthetic | They are produced by chemists in a laboratory |
Pure Substances | - fixed/definite composition, elements, & compounds
- composed of a single component
- has a constant composition regardless of the sample size and origin |
pure substance | cannot be broken down to other pure substances by any physical change |
Element | - consists of 1 type of atom
- can't be broken down by ordinary chemical means
pure substance
Ex. Ag = gold |
Compounds | consists of 2+ elements; chemically combined in a definite ratios
pure substance
Ex. CO = Carbon Monoxide |
Mixture | - 2+ substances physically mixed not chemically combined, composition varies; can be separated by psychical means
- mixtures can be liquid, solid, gas
Ex. salt & pepper shaker from Subway |
States of Matter | - solid
- liquid
- gas |
Solid has | - definite volume; definite shape
- particles lie close together
- particles arranged in a regular 3-dimensional array |
Liquid has | - definite volume; on definite shape
- particles are close together, but move randomly around, sliding past one another |
Gas has | - no definite volume or shape
- particles move randomly & are separated by a distance much larger than their size |
Properties of Matter | - Physical
- Chemical |
Physical Properties | - color, size, shape, melting point
- observed w/o changing its composition |
Chemical Properties | - flammability, reactivity
- observed & changed substance
- substance can be converted to another substance |
Changes of Matter | - physical
-chemical |
physical changes to matter.... | - melting, tearing
- change in state
- alters a substance w/o changing its composition |
chemical changes to matter..... | - chemical reaction
- converts one material to another
- burning paper; rusting |
disadvantage of the English System.... | units are not systematically related to each other & require memorization |
SI units | - based on the metric system,
- Systeme International
- International system of Units was formally adopted as the uniform system of units for science, 1960 |
Mass | - a measure of the amount of matter in an object
- stays the same |
Weight | - the force that matter feels due to gravity
- changes due to location |
2 units for volume | - cubic cm (object)
- mL (liquid) |
1ml = 1 cubic cm = 1 cc | |
Conversion Factor | term that converts a quantity in one unit to a quantity in another unit |
goal of a conversion factor.... | setting up the problem to make sure all unwanted units cancel |
in conversion factor, always arrange the factors so... | that the denominator in one term cancels the numerator in the preceding term |
Temperature | is a measure of how hot or cold an object is |
3 scales used in temperature | - Fahrenheit
- Celsius
- Kelvin |
Fahrenheit to Celsius equation | F = (1.8 x C) + 32 |
Celsius to Fahrenheit equation | C = (F - 32) / 1.8 |
Celsius to Kelvin | C = K - 273 |
Kelvin to Celsius | K = C + 273 |
Density | a physical property that relates the mass of a substance to its volume
g/mL |
density equation | D = M / V |
density of a substance depends on | temperature |
solid stat is __________ than the liquid state | more dense |
as the temperature __________, the density__________ | increases; decreases |
The ___________ of a substance determines whether it floats or sinks in a liquid. | density |
A ________ dense substance floats on a ______ dense liquid. | less; more |
equation for Specific Gravity | specfiic gravity = density of a substance (g/mL)/ density of H20 (g/mL) |
Units for Specific Gravity | has no units |
why does specific gravity have no units | all of the units get cancelled out while solving equation |
what is the density of water at 4 degrees Celsius | 1.00 g/ml |
the specific gravity of a substances equals___________ | its density, but with no units |