Matter

1. Matter 7-5.1, 7-5.2

2. Matter • Everything around you is matter • Matter is anything that has mass and takes up space

3. Atom • All objects are made of the same thing – atoms. • Atom: the smallest part of an element that has the chemical properties of that element • Are tiny particles that are much too small to be seen with a classroom microscope • They have mass and take up space

4. Element • All matter on Earth is made up of elements • Element: a pure substance that cannot be changed into a simpler substance • There are more than 100 known elements • Each element is made up of only one type of atom

5. Molecule • Two or more atoms can combine to form a molecule • Molecule: forms when two or more atoms are held together by a force called a chemical bond • May contain atoms of only one element (oxygen gas) but can also form when two or more different elements join together (water and carbon dioxide)

6. Compound • Is a pure substance composed of two or more elements that are chemically combined • Water and carbon dioxide are compounds • Compounds have different properties than the elements that form them

7. Molecule vs. Compound • All compounds are molecules but not all molecules are compounds • Molecules that cannot be compounds: hydrogen gas (H2), oxygen gas (O2), nitrogen gas (N2) • Not compounds because they are formed by a single element • Examples of compounds (are also molecules): NaCl, CO2, H2O • Are compounds because they are formed by more than one element • Are molecules because they are two or more atoms joined chemically

8. Pure Substance • Elements and compounds are both pure substances • Is a substance made up of only one kind of atom or molecule • Elements are made of only one kind of atom • Compounds are made up of more than one kind of atom, but only one kind of molecule

9. Mixtures • Forms when two or more pure substances are combined physically • Substances do not change or combine chemically • They keep their own individual properties • Substances in mixtures can be separated by physical means • Three common methods to separate mixtures: • Sifting • Filtration • Evaporation

11. Types of Mixtures • Heterogeneous mixture: not uniform throughout • Individual substances in such a mixture are easy to distinguish • Ex: granite • Homogeneous mixture: made up of substances that are evenly mixed • Cannot be visually distinguished • Solution: a homogeneous mixture in which the particles are so small they cannot be easily seen • Ex: salt water