Bell Ringer 8-24-09 Write everything you know about matter.

Re-Tests If you fail a major chapter test, you can retake it and I will average the two grades together. However, you must come in on your own time before or after school to retake tests. If you are out the day of the test or quiz, I put a zero in the computer until you make it up.

Chapter 2 Section 1 Describing Matter

What is matter? *Matter- anything that has mass and takes up space Everything around you is matter, including YOU!!  Air, plastic, metal, wood, glass, clothes, paper…

*A substance is a single kind of matter that is pure * Chemistry is the study of the properties of matter and how matter changes. *A substance is a single kind of matter that is pure - Same stuff inside Example: table salt, sugar

Matter has 2 properties: Physical properties Chemical properties

Physical property- a characteristic of a pure substance that can be observed without changing it into another substance Examples: hardness, texture, color, freezing point, melting point, state of matter, solubility, luster, ability to conduct heat and electricity

2. Chemical property- a characteristic of a pure substance that describes its ability to change into different substances Examples: burning, flammability, rust, tarnishing

Elements An element is a pure substance that cannot be broken down into any other substance by chemical or physical means. Elements are the simplest substances. Examples: Aluminum Copper Oxygen Hydrogen 9

What is the smallest possible piece of matter? An atom is the basic particle from which all elements are made. But even an atom can be broken down into smaller parts. Nucleus Electron Cloud 10

What happens when atoms combine? A chemical bond is formed when atoms combine. It is a force of attraction between 2 atoms. A molecule is a group of two or more atoms held together by chemical bonds. Carbon Dioxide 11

Compounds Most elements in nature are found combined with other elements. A compound is a pure substance made of two or more elements chemically combined in a set ratio. A chemical formula shows the elements in the compound and the ratio of atoms Ex: Carbon dioxide’s chemical formula is CO2 What is the chemical formula for water? ______ 12

Together- Silver sulfide- tarnish When elements combine and form compounds, they have different properties than the element did on its own. Ex: Sulfur- yellow solid Silver- shiny metal Together- Silver sulfide- tarnish 13

Mixtures A mixture is made of two or more substances that are together in the same place but not chemically combined. Each substance in a mixture keeps its individual properties. Ex: Soil 14

2 Types of Mixtures 1. Heterogeneous Mixture- you can see the different parts. Ex: a salad 2. Homogeneous Mixture- the parts are so evenly mixed that you cannot see the different parts. Ex: Lemonade A solution is an example of a homogeneous mixture. 15

Compound vs. Mixture A compound can be hard to separate but a mixture is usually easy to separate. Question: How do you think you could separate the parts of lemonade? 16