MATTER NOTES Matter is anything that has mass and volume. All matter has characteristics which are used to describe it. Some properties of matter never change and are used to identify unknown types of matter. These properties are called characteristic properties. Examples include melting point, boiling point, odor, taste, and chemical reactivity. Matter goes through two types of change. The first is a physical change. In this type of change, the form, shape or phase of matter changes, but the characteristic properties do not change. Examples are tearing, breaking, melting, boiling or freezing. The other type of change is a chemical change. In this type of change, matter forms new types of matter that have new and different characteristic properties. Examples include burning wood, mixing baking soda and vinegar. Adding zinc to hydrochloric acid to make zinc chloride and hydrogen gas. Matter comes in two main forms. The first is pure substances, which are types of matter where one molecule looks exactly like another molecule of the substance. Two types of pure substances are 1. Elements—which is matter made up of atoms that are all exactly alike. Examples are hydrogen, oxygen, carbon and iron. Its smallest part is an atom. 2. Compounds—matter made up of two or more elements chemically combined (bonded). Examples include water, salt, sugar and vinegar. Its smallest part is a molecule. The second form of matter are mixtures which are two or more elements and/or compounds that are mixed together but not chemically combined. If they don’t chemically combine, they keep the characteristic properties of the elements or compounds that they are made of , and they are easy to separate one from another. There are 1. Solutions—which have one material completely dissolved in another—Example salt water or soda pop. 2. Suspensions—matter where one material is mixed with another but the particles are big enough to identify and separate—Example Italian Salad Dressing. There are four phases of matter: 1. Gases—have no definite shape, no definite volume, their molecules are very, very far apart and the molecules are moving very, very rapidly. 2. Liquids—have no definite shape, have a definite volume, molecules are close together but move freely, and molecules are moving medium speed. 3. Solids—have a definite shape, have a definite volume, the molecules are packed tightly together, and the molecules vibrate back and forth slightly. 4. Plasma—a high energy phase of matter in which molecules move extremely fast. It is found in things like stars and lightning. Density is a measurement of how much mass is in a given volume. Its formula is D = M/V. It is a characteristic property because it is a ratio and never changes. If you decrease mass, you also decrease volume by the same ratio. It is important because it allows matter to form layers, with the most dense on the bottom and least dense on top Atoms are the smallest particle of an element that have all of its characteristic properties. Molecules are two or more atoms bonded together or chemically combined. There are three main sub-atomic particles 1. Protons—they are found in the nucleus, they have a mass of one, and they have a positive charge. Their job is to determine which type of element an atom belongs with. 2. Neutrons—they are found in the nucleus, they have a mass of one, and they have a zero charge. Their job is to determine which isotope of an element is present. 3. Electrons—they are found in a cloud orbiting the nucleus, they have a mass of almost zero, and they have a negative charge. Their job is to allow atoms to bond with other atoms. Isotopes are atoms with the same number of protons, but a different number of neutrons. To find the number of protons and electrons, look at the atomic number. Example Carbon, atomic number 6, has six protons and six electrons. To find the number of neutrons, round the atomic mass to the nearest whole number and subtract the number of protons. Example Sodium atomic number 11 has a mass of 22.990, which is rounded to 23. Twenty three minus 11 equals 12, so sodium has 12 neutrons. Chemical bonding is when atoms gain, lose, or share electrons to form compounds. There are two types of bonding to know: 1. Ionic bonding—where one atom loses an electron and becomes positively charged, and a second atom gains an electron and becomes negatively charged. The positive to negative attraction forms the bond. 2. Covalent bonding—where two or more atoms share electrons. The periodic table of elements is arranged in order of the number of protons that the element has in its nucleus. The rows are arranged with all elements with the same number of electron shells, and the columns are arranged with elements that have the same number of electrons in their outer energy shell.