Chem- Unit 1

Matter, Measurement, and Calculations

Chem Definition

study of the composition, structure, properties and reactions of matter

Matter

is another term for all the substances that make up the world

-anything that has mass and occupies space

Volume

a measurement of three-dementional occupied by sustance

Mass

a measurement of amount of matter in an object

Weight

a measurment of gravitational force on object

Classification of Matter: 1) Pure Substances

Elements and Compounds

1) Purse Substances: Elements

only has one kind of atom in form of homoatomic molecules

-on the periodic table

-graphite, diamonds,

-only paired with the same element

1) Pure Substances: Compound

pure substance consist of two ore more elements with defined composition of two or more different kinds of atoms in neuroatomic molecules

-different elements coming together

Classification of Mater: 2) Mixture

two or more chemically distinct components that do not react with each other and are mixed

homogenous or heterogenous

2) Mixture: homogenous

matter that has the same properties throughout the sample (sugar+ water)

-can not see the different substances seperated

2) Mixture: hetergenous

matter with properties that are not the same throughout the sample

(sand + water) -can see difference

Solutions

can be solid, liquid or gass

solutions= homogenous mixtures

Classification of Matter: 3)

Physical and Chemical

3) Physical

properties that don’t change the composition of matter being studied

-color, length, volume, capacity

3) Chemical

properties of substances that describe its ability to change into 1 or more new substances

-acidity, reactivity, flammability, toxicity

-release of energy, forms bubbles, color change, irreversibility, gas, precipitation, light

ex. magnesium under heat

Changes of State

the change to or from solid, liquid or gass

solid to liquid

melting (heat added)

liquid to vapor

evaporation (heat added)

vapor to condensation

liquid (cold added)

liquid to freezing

solid (cold added)

vapor to solid

deposition (cold added)

solid to vapor

sublimation (heat added)

precipitate

forming a solid

Measurement Units

Measurements are physical quantities used to

describe matter and its behavior.

• The earliest units. dimensions of the human body.

− Ex. Cubit

• Scientists use the metric system of a modification called the International System of Units (SI) as a worldwide standard.

Measurement

number identifying unit

-carry meaning contributing to its measurement resolution

resolution

refers to the quality that an instrument can be read

Known Digit

observed numerical values of marked lines

Estimated Values

estimated value of a number between marks

SF-Nonzero Digits

All nonzero numbers are significant.

SF- Leading Zeros

Zeros not preceded by nonzero numbers are not significant figures

SF Buried Zeros

Zeros located between nonzero numbers are significant figures

SF- Trailing Zeros

Zeros located at the end of a number are significant figures if a decimal point is present in the number

Calculations with SF: addition and subtractions

final answer with the same number if decimal places as the measurement with the fewest decimal places

12. 201 cm + 4.15 = 16.35

3dp. 2dp = 16.35 cm

Calculations with SF: multiplication and division

final answer with the same number of significant figures as the measurement with the fewest significant figures.

12m x 28.08 = 336

2sf. 4sf. = 340

Scientific Notation

Scientific notation is a method to express very large or very small numbers in scientific measurements or calculations.