3.+Matter+is+made+up+of+particles

MAJOR UNDERSTANDINGS 3.1a Substances have characteristic properties. Some of these properties include color, odor, phase at room temperature, density, solubility, heat and electrical conductivity, hardness, and boiling and freezing points. 3.1b Solubility can be affected by the nature of the solute and solvent, temperature, and pressure. The rate of solution can be affected by the size of the particles, stirring, temperature, and the amount of solute already dissolved. 3.1c The motion of particles helps to explain the phases (states) of matter as well as changes from one phase to another. The phase in which matter exists depends on the attractive forces among its particles. 3.1d Gases have neither a determined shape nor a definite volume. Gases assume the shape and volume of a closed container. 3.1e A liquid has definite volume, but takes the shape of a container. 3.1f A solid has definite shape and volume. Particles resist a change in position. 3.1g Characteristic properties can be used to identify different materials, and separate a mixture of substances into its components. 3.1h Density can be described as the amount of matter that is in a given amount of space. If two objects have equal volume, but one has more mass, the one with more mass is denser. 3.1i Buoyancy is determined by comparative densities. 3.2a During a physical change a substance keeps its chemical composition and properties. Examples of physical changes include freezing, melting, condensation, boiling, evaporation, tearing, and crushing. 3.2b Mixtures are physical combinations of materials and can be separated by physical means. 3.2c During a chemical change, substances react in characteristic ways to form new substances with different physical and chemical properties. 3.2d Substances are often placed in categories if they react in similar ways. Examples include metals, nonmetals, and noble gases. 3.2e The Law of Conservation of Mass states that during an ordinary chemical reaction matter cannot be created or destroyed. 3.3a All matter is made up of atoms. Atoms are far too small to see with a light microscope. 3.3b Atoms and molecules are perpetually in motion. The greater the temperature, the greater the motion. 3.3c Atoms may join together in well-defined molecules or may be arranged in regular geometric patterns. 3.3d Interactions among atoms or molecules result in chemical reactions. 3.3e The atoms of any one element are different from the atoms of other elements. 3.3f There are more than 100 elements. Elements combine in a multitude of ways to produce compounds that account for all living and nonliving substances. Few elements are found in their pure form. 3.3g The periodic table is one useful model for classifying elements. The periodic table can be used to predict properties of elements (metals, nonmetals, noble gases).