Chemistry – Lesson 1.2 Matter and Its Properties

I. Basic Building Blocks of Matter A.Fundamental building blocks of matter are atoms and molecules. B. Atom – the smallest unit of an element that maintain the properties of that element. 1. Element – a pure substance made of only one kind of atom. 2. Examples: carbon, hydrogen, oxygen

I. Basic Building Blocks (cont.) C.Molecule – smallest unit of a compound that retains all of the properties of that compound. 1. Compound – a substance that is made from the atoms of two or more elements that are chemically bonded. 2. Examples: carbon dioxide (CO 2 ), water (H 2 O), hydrogen (H 2 )

II. Properties and Changes in Matter A.General Information 1. Every substance has characteristics properties. 2. Properties can be used to distinguish or separate substances. 3. Sometimes property defines group or subgroup 4. Properties may help reveal the identity of unknown substances.

II. Properties and Changes (cont.) 5. Extensive Property a) depends on amount of matter present b) examples: volume, mass 6. Intensive Property a) does not depend on amount of matter present b) examples: melting point, density

II. Properties and Changes (cont.) B.Physical Properties and Physical Changes 1. Physical Property – characteristic that can be observed or measured without changing the identity of the substance. 2. Physical Change – change in substance that does not involve a change in the identity of the substance.

II. Properties and Changes (cont.) 3. Change of State – type of physical change. a) Three states of matter – solid, liquid, gas b) Changes of state – melting /freezing boiling / condensing

II. Properties and Changes (cont.) C.Chemical Properties and Chemical Changes 1. chemical property a) relates to a substance’s ability to undergo changes that transform it into different substances. b) examples: wood will burn, iron rusts

II. Properties and Changes (cont.) 2. Chemical change a) a change in which one or more substances are converted into different substances. b) examples: carbon + oxygen carbon dioxide iron + oxygen iron oxide (rust) 3. Chemical changes do not affect the total amount of matter.

II. Properties and Changes (cont.) D.Energy and Changes in Matter 1. Energy is almost always involved in physical and chemical changes. 2. Energy can be absorbed or released during a change. 3. Energy is not destroyed or created during change – Law of Conservation of Energy

III. Classification of Matter A.Mixtures 1. Mixture – a blend of two or more kinds of matter, each of which retains its own identity and properties. 2. Homogeneous mixture a) uniform in composition b) Ex: sugar dissolved in water 3. Heterogeneous mixture a) not uniform throughout b) Ex: soil, sand, salt

III. Classification of Matter (cont.) 4. Mixtures can be separated into individual components. B.Pure Substances 1. pure substance – substance that has a fixed composition and differs from a mixture in two ways a) every sample has exactly the same properties. b) every sample has exactly the same composition.

III. Classification of Matter (cont.) 2. Pure substances are either compounds or elements. a) compound – can be decomposed or broken down into two ore more simple compounds or elements by a chemical change. b) element – can not be decomposed or broken down by chemical reactions.