Chemistry Unit 1 Study Guide – Flashcards

Three states of matter: solid, liquid and gas. -Solid: constant shape, constant volume, particles bound together rigidly. -Liquid: variable shape, constant volume, particles bound togetehr but flexibly. -Gas: variable shape, variable volume, particles not bound together.

Element: a substance that cannot be separated or broken down into simpler substances by chemical means; all atoms of an element have the same atomic number. (are pure substances that contain only one kind of atom). Molecules: the smallest unit of a substance that keeps all of the physical and chemical properties of that substance; it can consist of one atom or two or more atoms bounded together. (usually consists of two or more atoms combined in a definite ratio). Pure Substance: a sample of matter, either a single element or a single compound, that has definite chemical and physical properties. (every pure substance has characteristic properties that can be used to identify it). Compounds: a substance made up of atoms of two or more different elements joined by chemical bonds. (compounds are composed of more than one kind of atom). Mixture: a combination of two ore more substances that are not chemically combined. (a sample of matter that contains two or more pure substances). 1. Homogenous: the particles are evenly distributed the particles will not separate over time does not diffract light called a solution. 2. Heterogeneous: the particles are NOT evenly distributed. Suspensions will separate over time (oil & water) Colloids are stable heterogeneous mixtures that will NOT separate over time.

-Chemical Properties: are properties of an element or compound in chemical reactions. -Physical Properties: are properties of an element or compound that can be observed without a chemical reaction of the substance.

-Physical changes: Physical changes are concerned with energy and states of matter. A physical change does not produce a new substance. Changes in state or phase (melting, freezing, vaporization, condensation, sublimation) are physical changes. Examples of physical changes include crushing a can, melting an ice cube, and breaking a bottle. Chemical changes: Chemical changes take place on the molecular level. A chemical change produces a new substance. Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan, and mixing hydrochloric acid and sodium hydroxide to make salt and water.

Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan, and moldy cheese.

When you are measuring, you MUST read one decimal place further than is marked in your measuring device. Ex: measured 3.4; one decimal (guess) 3.41

23.56 4 All nonzero digits are significant. 23.560 5 Trailing zeros are significant when a decimal point is shown. 1000 1 Trailing zeros are not considered significant when no decimal point is shown. 1000. 4 Showing the decimal point indicates that the preceding zeros are significant. 500.01 5 Zeros between nonzero digits are significant. 0.0078 2 Leading zeros are not significant. 12.2300 6 Example

D = Density: measured in g/mL M = Mass: measured in grams V = Volume: measure in mL Find density: mass/volume

Prefix Symbol Meaning Kilo k thousand Centi c hundredth Milli m thousandth Micro u millionth

Review lab safety packet.