Chapter 2 - Matter NOTES

LT 1 – I can identify elements and compounds. ▪ WHAT IS MATTER? – Anything that has mass and takes up space – Every sample of matter is either an element, a compound, or a mixture ▪ ELEMENTS – A substance that cannot be separated or broken down into simpler substances by chemical means – Atom – the smallest unit of an element that maintains the chemical properties of that element – EACH ELEMENT IS MADE OF ONE KIND OF ATOM – Elements are represented by symbols (periodic table is a list of elements) – Molecule – a group of atoms that are held together by chemical forces (you can have a molecule of an element or of a compound)

▪ COMPOUNDS – A substance made up of atoms of two or more different elements joined by chemical bonds – Each molecule of a compound contains two or more elements that are chemically combined. – Have unique properties – Chemical formulas represent compounds O 2 - represents a molecule of the element, Oxygen C 16 H 10 N 2 O 2 - represents a molecule of the compound, Indigo

LT2: I can define substances and mixtures. PURE SUBSTANCE Matter that has definite chemical and physical properties Can be an element or a compound MIXTURE A combination of two or more substances that are not chemically combined. Classified by how well the substances mix HETEROGENEOUS MIXTURE Substances are not evenly distributed (ex. Salad) HOMOGENEOUS MIXTURE Substances are evenly distributed (ex. Vinegar) Miscible – able to be mixed (ex. gasoline) Immiscible – mixture forms layers (ex. oil and water) Gases can mix with liquids (ex. carbonated drinks)

LT 3: I can compare and contrast solutions, colloids, and suspensions. ▪ SOLUTIONS – A homogeneous mixture of particles so small that they cannot be seen with a microscope and will never settle – Uniformly mixed – Examples: vinegar, soda ▪ COLLOIDS – A type of mixture that never settles – Examples: paint, jello, fog, smoke – Tyndall Effect: the scattering of light by colloidal particles ▪ SUSPENSIONS – Heterogeneous mixture containing a liquid which visible particles settle – Examples: muddy pond water, river deltas

LT 4: I can identify substances using physical properties. ▪ Physical Properties – Characteristics that can be observed without changing the identity of the substance – Help identify substances – Can be observed or measured – Help determine uses – Color – Mass – Shape – Density – Melting/Boiling/Freezing points – Strength – Hardness – Magnetism

LT 5: I can identify substances using chemical properties. ▪ Chemical Properties – Describes how a substance changes into a new substance, either by combining with other elements or y breaking apart into new substances. – Flammability – Reactivity – Heat of combustion – pH

LT 6: I can compare and contrast physical and chemical changes. ▪ PHYSICAL CHANGE – Affects one o more physical properties of a substance without changing the substance. – DO NOT change a substance’s identity ▪ Melting, cutting, crushing, dissolving, sanding, breaking, ripping, tearing… ▪ CHEMICAL CHANGE – Happens when one or more substances are changed entirely into new substances that have different properties. – Happen everywhere – Form NEW substances – Can not be reversed by physical changes – Oxidizing, burning, dying, digesting, baking, cooking, – CAUSE color changes, fizzing/foaming, production of sound, heat, light, or odor ▪ MIXTURES CAN BE SEPARATED BY PHYSICAL CHANGES, BUT COMPOUNDS MUST BE BROKEN DOWN BY CHEMICAL CHANGES!