Elements, Compounds, and Mixtures. Matter: Properties and Changes

Transcription

1 Elements, Compounds, and Mixtures Matter: Properties and Changes

2 Warm up Observe the pictures and use the following terms to name them: element, compound, or mixture. Explain your answer.

3 Warm up answers mixtures element compound

4 Lesson Objectives Classify matter as elements, compounds, or mixtures based on how the atoms are packed together in arrangements. Identify the different kinds of properties used to describe matter. Essential Question How does the arrangement of atoms affect the classification of matter?

5 Properties of Matter Chemistry is the properties of matter and how matter changes. The properties and changes of any type of matter depend on its makeup. Some types of matter are substances and some are not. Substance is a single kind of matter that is pure, meaning it always has a specific composition and properties. Table salt, sugar, and baking soda are examples of pure substances because has the same composition and properties no matter where it comes from

6 Properties of Matter Every form of matter has two kinds of properties: physical and chemical A physical property for oxygen is that it is a gas at room temperature A chemical property for oxygen is that it reacts with iron to form rust.

7 Physical Properties of Matter Physical properties is a characteristic of a pure substance that can be observed without changing it into another substance. Types of physical properties texture color flexibility physical state (solid, liquid, or gas) freezing point boiling point odor ability to conduct electricity magnetism dissolve in water

8 Chemical Properties of Matter Chemical property is a characteristic of a pure substance that describe its ability to change into different substances. Types of chemical properties flammability burning rust tarnish combustibility

9 Elements Element is a pure substance that cannot be broken down into any other substances by chemical or physical means. is the simplest substance can be identified by it specific physical and chemical properties

10 Elements What is the smallest possible piece of matter? Atom is the basic particle from which all elements are made. Different elements have different properties because their atoms are different. Atom model

11 Parts of an atom

12 Parts of an Atom Nucleus is the center of the atom. The nucleus of most atom is made up of two kinds of particles: proton and neutrons Protons carry a positive (+) charge. Charge is an electrical property that can be either positive or negative. Neutrons have no charge. The mass of protons and neutrons are measured in atomic mass units (amu). Each proton or neutron has a mass of about 1 amu. Electrons are subatomic particles that exist in an area outside the nucleus called the electron cloud. They have a negative (-) charge. The mass of electrons is insignificant compared to the mass of protons and neutrons.

13 Elements What happens when atoms combine? When atoms combine they form a chemical bond, which is the force of attraction between to atoms. Atoms form molecules that are groups of two or more atoms held together by chemical bonds.

14 Compounds A compound is a pure substance made of two or more elements in the compound and the ratio of atoms. Is represented by a chemical formula, which shows the elements in the compound and the ratio of atoms. Example of chemical formula: CO2 (carbon dioxide), H20 (water) When elements are chemically combined, they form compounds having properties that are different from those of the uncombined elements. Examples: Ag2S (silver sulfide), C12H22O11 (table sugar)

15 Compounds Ag (silver) Ag2S (silver sulfide) S (sulfur)

16 Mixtures Mixture is made of two or more substances - elements, compounds, or both - that are together in the same place but are not chemically combined. Each substance in a mixture keeps its individual properties. The parts of a mixture are not combined in a set ratio. Soil

17 Types of Mixtures I. Heterogeneous Mixtures Is a mixture in which pure substances are unevenly distributed throughout the mixture. The individual substances are easy to distinguish. II. Homogeneous Mixtures Is a mixture in which substance are evenly distributed throughout the mixture. Example of homogeneous mixture is a solution. Solution can be liquid (ice tea) gas (oxygen) solid (Brass - copper and zinc)

18 Homogeneous mixtures - Solution A solution is a type of homogeneous mixture in which one substance is completely dissolved in another substance. Solutions are usually liquids. Example: sugar dissolve in water Solution has two part: solvent is the substance that does the dissolving (water) solute is the substance that dissolves (sugar)

19 Types of Mixture

20 Separating Mixtures A compound can be difficult to separate into its elements, but a mixture is usually easy to separate into its components because each components keeps its own properties. Methods use to separate mixtures: magnetic attraction sifting filtration distillation evaporation

21 Methods to Separate Mixtures Sifting separates the solid parts of a mixture by particles size. A screen or similar devices is often used to sift materials

22 Methods to Separate Mixtures Filtration separates a solid from a liquid in a heterogeneous mixture.

23 Methods to Separate Mixtures Evaporation can be used to separate a solid from a liquid in a solution.

24 Review