1.2 Matter and Its Properties

1. 1.2 Matter and Its Properties

2. Terms • Matter- anything that has mass and volume • Atom- smallest unit of an element that keeps the properties of element • Element- pure substance made of only one type of atom • Compound- substance made of 2 or more types of atoms that are chemically bonded • Molecule- type of compound in which bonds are covalent bonds

3. Properties of Matter • chemists use characteristic properties to tell substances apart and to separate them • some properties define a group of substances

4. Types of Properties • Extensive- depend on the amount of matter • Ex: volume, mass, amount of energy • Intensive- do not depend on the amount • Ex: density, boiling point, ability to conduct

5. Types of Properties • Physical- characteristics that can be observed or measured without changing the identity of a substance • Ex. melting point, boiling pt • Chemical- relates to a substances ability to undergo changes that transform it into a different substance • Easiest to see when a chemical is reacting

6. Physical Changes in Matter • change in a substance that doesn’t change the identity of the substance • Ex. grinding, cutting, melting, boiling • Includes all changes of state (physical changes of a substance from one state to another)

7. Solid • definite volume • definite shape • atoms are packed together in fixed positions • strong attractive forces between atoms • only vibrate in place

8. Liquid • definite volume • indefinite shape • atoms are close together • atoms can overcome attractive forces to flow

9. Gases • indefinite volume • indefinite shape • atoms move very quickly • atoms are far apart • pretty weak attractive forces

10. Changes of State

11. Plasma • high temperature state in which atoms lose their electrons • Ex. the sun

12. Chemical Changes in Matter • a change in which a substance is converted into a different substance • same as chemical reaction • doesn’t change the amount of matter present • reactants- substances that react • products- substances that form

13. Energy Changes in Matter • when any change occurs, energy is always involved • energy can be in different forms (light, heat, etc.) • energy is never destroyed or created (law of conservation of energy)

14. Energy Changes in Matter • Exothermic Reaction- reaction that gives off energy (feels warm on outside) • Endothermic Reaction- reaction that uses up energy (feels cold on outside)

15. Separation Techniques • Filtration- solid part is trapped by filter paper and the liquid part runs through the paper • Vaporization- where the liquid portion is evaporated off to leave solid

16. Separation Techniques • Decanting- when liquid is poured off after solid has settled to bottom • Centrifuge- machine that spins a sample very quickly so that components with different densities will separate

17. Separation Techniques • Paper Chromatography- used to separate mixtures because different parts move quicker on paper than other

18. 1.3 Elements

19. Elements • elements are pure substances • organized by properties on periodic table • each square shows the name and letter symbol for each element • usually the symbols relate to the English names but some come from older names (usually Latin) • Ex: gold’s symbol is Au from aurum • Ex: iron’s symbol is Fe from ferrum

20. Periodic Table • Groups • also called families • vertical columns • numbered 118 • have similar chemical properties • Periods • horizontal rows • properties changes consistently across a period

21. Periodic Table

22. Periodic Table • two rows below the periodic table are the lanthanide and actinide series • these rows fit after #57 and #89 • they are only at the bottom to keep the width of the chart smaller

23. Types of Elements • Metals • an element that is a good conductor of electricity • at room temperature, most are solids • malleable- can be rolled or hammered into sheets • ductile- can be made into wire • high tensile strength- can resist breakage when pulled • most have silvery or grayish white luster

24. Types of Elements • Nonmetals • an element that is a poor conductor of heat and electricity • many are gases at room temperature • some are solids: usually brittle, not malleable

25. Types of Elements • Metalloids • an element that has some characteristics of metals and nonmetals • appear along staricase line • B, Si, Ge, As, Sb, Te • all are solids at room temperature • less malleable that metals but less brittle than nonmetals • are semiconductors

26. Types of Elements • Noble Gases • generally unreactive gases • in far right column of periodic table