Chemistry intro

percent error

calculated to compare experimental value w correct/accepted value

%error = Ve - Va/Va x 100

Accuracy

How close an experimental value is the the correct/accepted value

Precision

How close experimental values are to eachother

Significant figures

contains all certain digits & one estimated digit, shows precision of measurement

In sig fig, all non zero digits are ___

sig figs

in sig fig, Imbedded zeros ___

always are sig figs, 16.07 has 4 sig figs

In sig fig, Leading zeros are ___

not sig figs. 0.001 have 1 sig fig

Trailing zeros are __

only sig figs if # has a decimal place, 1.800 has 4 sig figs

placeholder zeros are __

not sig figs, 1000 has 1 sig fig

how can u make placeholder zeros a sig fig?

add a decimal to the end

When adding & subracting, how do u apply sig figs

answer has same # of sig figs as number with least number of decimal places

When multiplying and dividing, how do u apply sig figs

goes by least # of sig figs

Ambiguous numbers

use scientific notation to show sig figs

9.450 × 10^6

decimal place moves 6 to left

7.61 × 10^4

decimal moves 4 to right

Metric conversion rules

1. biggest number gets a zero

2. count spaces - add zeros

Dimensional analysis rule

always stop at base unit

Density equation

D = M/V (g/ml or cm³)

Matter

has mass and takes up space, composed of atoms

Pure substances

elements & compounds

mixtures

heterogeneous and homogeneous

Compounds

two or more different atoms bonded together, always same composition

Solid

fixed volume and shape

liquid

definite volume, fits shape of container

Gas

no fixed shape/volume

plasma

gas particles with charge

Physical properties

changes in physical appearance

no changes in identity

Chemical properties

changes in identity of a substance

mixture

material with variable composition

homogeneous

uniform

heterogenous

not uniform