Properties of Matter

Properties of Matter chemists use characteristic properties to tell substances apart and to separate them some properties define a group of substances

Types of Properties Extensive- a property that depends on the amount of matter Ex: volume, mass, amount of energy Intensive- a property that does not depend on the amount of matter Ex: density, boiling point, ability to conduct electricity

A. Extensive vs. Intensive Examples: boiling point volume mass density Conductivity temperature

Types of Properties Physical property- characteristics that can be observed or measured without changing the identity of a substance Chemical property- relates to a substance’s ability to undergo changes that transform it into a different substance Easiest to see when a chemical is reacting

B. Physical vs. Chemical physical chemical Examples: melting & boiling point flammable density magnetic tarnishes in air

Physical Changes in Matter change in a substance that doesn’t change the identity of the substance Ex. grinding, cutting, melting, boiling Includes all changes of state (physical changes of a substance from one state to another)

Solid definite volume definite shape atoms are packed together in fixed positions strong attractive forces between atoms only vibrate in place

Liquid definite volume indefinite shape atoms are close together atoms can overcome attractive forces to flow

Gases indefinite volume indefinite shape atoms move very quickly atoms are far apart pretty weak attractive forces

Chemical Changes in Matter A change in which a substance is converted into a different substance Also known as a chemical reaction Doesn’t change the amount of matter present (Law of Conservation of Mass) reactants- substances that react products- substances that are formed

mercury + iodine  mercuric iodide

Signs of a Chemical Change Heat is released (gas is given off) or absorbed (feels cold) Bubbles form without heating Color change without an apparent cause

B. Physical vs. Chemical chemical physical Physical Examples: rusting iron dissolving in water burning a log melting ice grinding spices Decomposing tree

Physical vs Chemical Color Change What is the difference between the cause of color change in the two pictures below?

What types of matter are there? Element Compound Homogeneous Mixture Heterogeneous Mixture

Atom- smallest unit of an element that keeps the properties of element Evolution of the atom

Element- pure substance made of only one type of atom

TNT Salt Caffeine Sugar Compound- substance made of 2 or more types of atoms that are chemically bonded TNT Salt Caffeine Sugar

Pure Substances every sample has same: are made of: characteristic properties composition are made of: one type of atom: element Ex: iron, gold, oxygen 2 or more types of atoms: compound Ex: salt, sugar, water

Which are pure substances?

Mixtures blend of 2 or more types of matter each component keeps its own identity and properties the components are only physically mixed can be separated using physical means properties of the mixture are a combination of the properties of the componenent’s properties

Homogeneous Mixtures also called solution uniform in composition no visible parts Ex: vinegar salt water brass

Heterogeneous Mixtures Ex: soil concrete blood chocolate chip cookies sand in water iced tea with ice not uniform in composition visible parts

Mixtures

Practice Determine whether each of the following is element, compound, homogeneous mixture or heterogeneous mixture. air wood chlorine granite aluminum sugar in water blood sucrose stainless steel sodium chloride brass whole milk apple table salt soft drinks vinegar concrete sodium baking soda (NaHCO3) gravel