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Unit 2 Matter World of Chemistry Chapter 2 Matter.

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1 Unit 2 Matter World of Chemistry Chapter 2 Matter

2 Chapter Objectives: Identify the composition of matter Distinguish between elements, compounds, and compounds Define the three states of matter Distinguish between physical and chemical properties Distinguish between physical and chemical changes Distinguish between mixtures and pure substances Identify methods to separate mixtures

3 What is matter? Matter: anything that mass and occupies space (volume) Matter is classified into two categories: 1. Pure substance: a substance that is composed of one type of element or compound; cannot be separated (aluminum foil, water) 2. Mixture: a substance that is composed of two more elements or compounds; can be separated (Ex. brass, Gatorade)

4 Pure Substance (Liquid water) Mixture (salt water = NaCl in H 2 O)

5 What is matter? Element: a substance made with only one type of atom (H, He, Li, etc.) Atom: the smallest form of an element that retains its chemical properties; tiny particles Molecule: a combination of two or more atoms (O 2, H 2, H 2 O, CH 4 ) Compound: a substance composed of two or more different atoms (CH 4, AlCl 3 )

6 Element Atom 24K gold is a pure substance. It is made of only gold atoms

7 Molecules and Compounds sulfur dioxide, SO 2 S O O Cl chlorine, Cl 2 penicillin,with carbon, nitrogen, sulfur, oxygen, hydrogen atoms

8 Types of Mixture Homogeneous (solution): a mixture that has a uniform appearance – Ex’s: salt water, brass (alloy), air – Alloy: a mixture of metal elements Heterogeneous: a mixture that contains regions with different physical properties – Ex’s: dirt, vegetable soup, oil/water

9 Identifying the following mixtures as homogeneous or heterogeneous

10 Physical vs. Chemical Physical property: characteristics that describes a substance – color, odor, texture, taste – mass, volume – density, boiling point, melting point – physical state (gas, liquid, solid) Physical change: change in one or more physical properties without changing its chemical composition

11 Physical Examples Physical properties – bubblegum has a pink color – carbon monoxide is odorless – the density of water is 1.0g/mL – Ms. Cipolla is 1.54m Physical changes – cutting wood – breaking glass – melting silver – boiling water

12 Physical vs. Chemical Chemical property: characteristics that describe how a substance will change into a new substance – flammability, radioactivity, oxidizes – reactivity with water, acids, bases, air Chemical change: change that occurs when a substance turns into a new substance with different physical and chemical properties

13 Chemical Examples Chemical properties – potassium violently reacts in water – silver tarnishes in air – hydrogen gas is produced from zinc in acid – uranium-235 decay Chemical changes – lighting a match – photosynthesis – baking bread – bleaching clothing

14 States of Matter Matter exists in one of three states (or phases): 1.Solid – rigid, fixed shape and volume 2.Liquid – fluid, no defined shaped, fixed volume 3.Gas – random motion, no defined shape or volume State changes:


16 Separating Mixtures Various techniques can be used to separate mixtures: – Distillation: used to separate substances in a solution based on differences in boiling point – Filtration: used to separate solid substances from a mixture – Magnetization: used to separate based on magnetic properties

17 Distillation – a liquid solution is heated. Components are separated out when the temperature reaches their individual boiling point. These now gases cool off as they pass through a condenser and turn back into a liquid where they are collected in a separate container. condenser liquid solution vapor separated material

18 Filtration – a heterogeneous mixture (usually composed of a liquid and solid) is passed through a filter, i.e. paper. Material that is small enough to pass through the filter is collected in a separate container.

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