Chapter 2 Matter

Matter: Anything that has mass and takes up space Atom: is the basic unit of matter Mass: is the amount of material an object has (do not confuse with weight) Chemistry: is the study of matter and how it changes Element: is a substance that cannot be separated into other kinds of substances (lead into gold)

Physical Property: is a characteristic of a substance that can be observed without changing the substance into a different substance (ice/liquid water/steam) Compound: is a substance made up of atoms of different elements Molecule: is the smallest particle of a substance that has the all the properties of the substance Chemical Property: is a characteristic that describes how a substance changes into a different substance (elements combine with each other in chemical reactions) Chemical bonds: store energy

Compounds

Chemical Formula Represents compounds Example: Molecule of indigo Dye for blue jeans C16H10N2O2 Three molecules of table sugar 3C12H22O11

Pure Substance A sample of matter, either a single element (O) or a single compound (H2O), that has definite chemical and physical properties Elements: Na or Cl Compound: NaCl Elements and compounds are pure substances, but mixtures are not.

Mixtures Classified by how well the substances mix Heterogeneous: mixture that is NOT evenly distributed Salad Homogeneous: mixture that is evenly distributed Vinegar and water Gasoline (hundreds of liquids that are miscible) Carbonated beverage

Mixture

Properties of Matter Physical: characteristics that can be observed without changing the identity of the substance Density Melting point (solid to a liquid) Boiling point (liquid to a gas) Reactivity (chemical property) Can be separated by physical means

Density Ratio of the mass of a substance to its volume D = mass/volume = m / v

Chemical Property Reactivity: the capacity of a substance to combine chemically with another substance Describes how a substance changes into a new substance, either by combining with other elements or by breaking apart into new substances Flammability (ability to burn) Iron and oxygen yielding rust Na and Cl yielding salt (NaCl) Some are reversible Example of carbonic acid in soda

Changes of Matter Physical change affects one or more physical properties of a substance without changing the identity of the substance Melting of ice (solid to liquid) Crushing of a can Dissolving of sugar in water Dissolving of CO2 in water Dissolving of air in ice cream (soft ice cream)

Changes of Matter Chemical change happens when one or more substances are changed into entirely new substances that have different properties (new substance has formed). Digesting of food Burn with oxygen Na and Cl to form NaCl Iron rusting Copper turning green