Chapter 2 - Matter Chem 6 Notetaker

Transcription

1 Chapter 2 - Matter Chem 6 Notetaker Name: Group: Date: Directions: Use the textbook to complete the following notes. Terms in italics are vocabulary terms. Their definitions should be memorized and understood. 2.1 The Particulate Nature of Matter Matter can be defined as the stuff of which the universe is composed All matter must have _ mass and must take up space (volume). The Atomic Nature of Matter All objects are made of tiny particles called atoms which can be seen in the images developed by a device called a scanning tunneling microscope 2.2 Elements and Compounds The most important idea in chemistry is: matter is composed of tiny particles called atoms All matter is made of about 100 different kinds of atoms. Compounds Compounds are substances made of_ two or more different atoms bonded together in a specific way with a fixed (consistent) ratio of elements. For example, H 2 O is a molecule made of 2 hydrogen atoms bonded to 1 oxygen atom. Every water molecule has the exact same ratio of elements and has the same arrangement of atoms.

2 Compounds made of the same elements have very different chemical properties. For example, H 2 O (water) is the most important liquid on Earth and H 2 O 2 (hydrogen peroxide) is used to treat cuts and bleach hair. Similarly carbon dioxide is exhaled by humans as a waste product and is used by plants to to make oxygen while carbon monoxide (CO) is a poisonous gas. A molecule is made up of _ atoms that are stuck together. Elements Elements are substances made of _ only one kind of atom. 2.3 The States of Matter The three states of matter that we use in chemistry are _ solids, liquids and gases Fixed shape? (Does it keep the same shape without breaking) Fixed volume? (Does it always take up the same amount of space) Solid yes yes Liquid no yes Gas no no Gases are made of mostly empty space and can be squeezed (compressed) to a smaller volume, however, liquids and solids have particles which are already tightly packed so they are incompressible (they cannot be squeezed to a smaller volume) Generally, solids take up less space (have a smaller volume) than liquids but water is an important exception. 2.4 Physical and Chemical Properties and Changes Typical examples of physical properties include _ odor, color, volume, state (solid, liquid, and gas), density, melting point and boiling point.

3 A physical change involves a change in one or more physical properties but no change in the _ fundamental components that make up the substaces. The most common physical changes are changes of _ state. solid liquid gas A chemical change involves a change in in the fundamental components of the substance, a given substance changes into a different substance. Chemical changes are called reactions. Examples of chemical changes are _ silver tarnishes by reacting with substaces in the air, a plant forms a leaf by combining various substances from the and soil. Electrolysis (or electrohydrolysis) is the process of using electricity to split water molecules (H 2 O) into hydrogen (H 2 ) and (O 2 ) 2.5 Mixtures and Pure Substances Virtually all of the matter around us consists of _ mixtures. Mixtures A mixture is something that has a variable composition. Examples of mixtures are _ wood, soda, coffee, water from the earth, air. The mixture that surrounds us is air and it is made of _ nitrogen, oxygen, water vapor, argon, carbon dioxide, neon, helium. A mixture of metals is called an _ alloy. It is not a compound because it has a variable composition (it is not exactly the same throughout). Pure Substances A mixture has a variable composition but a pure substance has _ the same composition throughout. Pure substances are either _ elements or _ compounds. Examples of pure substances are oxygen (element(, nitrogen (element), water (compound), carbon dioxide (compound), argon (element), and other pure substances.

4 Mixtures can be separated into _ pure substances. Homogeneous and Heterogeneous Mixtures The two types of mixtures are heterogeneous and homogeneous. Another name for a homogeneous mixture is a solution. The composition of a homogeneous mixture is uniform (the same throughout). A heterogeneous mixture contains regions that have different properties from other those of regions 2.6 Separation of Mixtures Mixtures can be separated into pure substances by a process of distillation and _ filtration. Distillation separates pure substances by _ boiling. Filtration separates pure substances by using a filter paper or mesh. The diagram below shows the organization of matter:

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