chemistry quiz 8/19 sadge

scientific method

observation --> representation (hypothesis) --> interpretation (experiment) --> theory/ law/ principle

theory

an explanation for an aspect of the natural world (or just explanation for laws and principles)

law

concise statement of describing what happens when certain conditions are present

principle

an absolutely proven law

matter

anything that occupies space and has mass

substance

a form of matter that has a definite composition and distinct properties

mixture

a combination of two or more substances in which the substances retain their distinct identities

homogenous mixture

in which the composition of the mixture is the same throughout

heterogenous mixture

composition is not uniform

element

a substance that cannot be separated into simpler substances by chemical means

compound

a substance composed of atoms of two or more elements chemically united in fixed proportions

physical property

property that can be measured and observed without changing the composition or identity of a substance (without going through chemical reactions)

chemical property

properties observed through chemical reactions

extensive property

depends on how much matter is being considered

intensive property

does not depend on how much matter is being considered

macroscopic properties

properties that can be measured directly

microscopic properties

on the atomic or molecular scale, must be determined by an indirect method

guidelines for significant figures

1. zeros to the left of the first nonzero digit are not significant2. zeros to the right of the first nonzero digit are significant3. for numbers without decimal points, trailing zeros make the number unable to make sure of its significant figures

accuracy

how close a measurement is to the true value of the quantity that was measured

precision

how closely two or more measurements of the same quantity agree with one another