What are the three parts that make up atoms?

1. S-88 Students will investigate our current understanding of the atom. What are the three parts that make up atoms? Which of the three are most important in determining what element an atom is? Which of the three are most important in determining how an element reacts with other elements?

2. S-89 Students will investigate our current understanding of the atom. What is the charge on each of the following parts of the atom? Proton Neutron Electron

3. SPS1 Students will investigate our current understanding of the atom. SPS2 Students will explore the nature of matter, its classifications, and its system for naming types of matter. SPS6 Students will investigate the properties of solutions. Chapter 2 Properties of Matter

4. Why are elements and compounds classified as pure substances? How do mixtures differ from pure substances? What is the main difference among solutions, suspensions, and colloids? 2.1 Classifying Matter

5. 2.1 Classifying Matter Why are elements and compounds classified as pure substances? • Pure substance – matter that always has the same compositions • Same number of elements • Combined the same way • Has the same properties • Either elements or compounds Glucose

6. 2.1 Classifying Matter Why are elements and compounds classified as pure substances? • Element – can not be broken down chemically • Atom – smallest particle of an element • Found on the periodic table • Different elements have different atoms • Elements are represented by symbols made of one of two letters • First is a Capital letter, second lower case

7. 2.1 Classifying Matter Why are elements and compounds classified as pure substances? • Compounds – made of two or more elements combined chemically • Same elements in the same ratio combined in the same pattern • Very different property from the elements that make them • Table Salt • Sodium – silver metal that explodes on contact with water • Chlorine – poisonous gas

8. 2.1 Classifying Matter How do mixtures differ from pure substances? • Mixture – two substances that are combine with no fixed composition • Not chemically combined • Can be • Heterogeneous Mixture – parts of the mixture are noticeably different from one another • Sand, muddy water, soil, granite • Homogeneous Mixture – (solution) parts are evenly distributed • Alloys, salt water, peroxide solution

9. 2.1 Classifying Matter What is the main difference among solutions, suspensions, and colloids? • Mixtures can be classified by the size of the largest particles • Solution – very small particles – this is a homogeneous mixture • Suspension – large particles – a heterogeneous mixture that separates into layers over time • Colloid – intermediate size particles – do not separate into layers, but scatter light like a suspension

10. 2.1 Classifying Matter

11. What are some examples of physical properties? How can knowing the physical properties of matter be useful? What processes are used to separate mixtures? 2.2 Physical Properties

12. 2.2 Physical Properties What are some examples of physical properties? • Physical property – can be observed or measured without changing the composition of the substance • Viscosity – the resistance of a liquid to flow • Conductivity – ability to allow heat to flow • Malleability – ability to be hammered without shattering or breaking • Hardness – how difficult it is to scratch a substance

13. 2.2 Physical Properties What are some examples of physical properties? • Physical property • Melting and Boiling Points • Density – mass divided by volume

14. 2.2 Physical Properties How can knowing the physical properties of matter be useful? • Physical properties are used to • Identify materials – items are tested and compared to known properties • Choose materials for specific purposes – based on what properties are needed

15. 2.2 Physical Properties What processes are used to separate mixtures? • Physical properties are used to • Separate the substances in a mixture • Filtration – separation based on size of particles • Distillation – separation based on differences in boiling points • Physical change – when some of the properties of a substance change, but the substance remains the same • Sharpening a pencil, melting ice, cutting hair

16. When can chemical properties be observed? What observations might indicate that a chemical change has occurred? What is the difference between chemical and physical changes? 2.3 Chemical Properties

17. 2.3 Chemical Properties When can chemical properties be observed? • Chemical Property – the potential of a substance to undergo a reaction • Can only be observed when the substance undergoes the reaction • Examples • Flammability – ability to react with oxygen • Reactivity – how a substances combines chemically with another substance

18. 2.3 Chemical Properties What observations might indicate that a chemical change has occurred? • Three common signs that a chemical change has occurred • Change in color • Production of a gas • Formation of a precipitate • Precipitate – solid formed when two liquids are mixed

19. 2.3 Chemical Properties What is the difference between chemical and physical changes? • How to tell if the change is chemical or physical • Chemical change – the substance changes • New chemical properties • Some new physical properties • Physical change – the substance stays the same • Same chemical properties • Same intrinsic chemical properties • Intrinsic – those that can be used to identify the substance • Density, conductivity, viscosity