REVIEW: ALL ABOUT MATTER. August 25, 2016

Transcription

1 REVIEW: ALL ABOUT MATTER August 25, 2016

2 Review Questions: 08/25/ How is matter classified? 2. How can we tell the difference between different types of matter? 3. Write down 5 different types of descriptions.

3 Big Idea 2: Chemical and physical properties of materials can be explained by the structure and arrangement of atoms, ions, or molecules and the forces between them

4 How is matter classified?

5 Classification of Matter Matter is anything that has mass and occupies space. We can classify matter based on whether it s solid, liquid, or gas.

6 Pure Substances Element composed of identical atoms EX: copper wire, aluminum foil

7 Molecule a combination of 2 or more atoms (same or different) that are covalently bonded. A molecule is the smallest particle of a substance which exhibits the physical and chemical characteristics of the substance. Diatomic molecules of elements : H 2 O 2 Cl 2 N 2 F 2 Br 2 I 2

8 Compounds composed of 2 or more elements in a fixed ratio properties differ from those of individual elements EX: table salt (NaCl)

9 Compounds Slight differences in combinations of atoms can have large difference in properties H 2 O- water H 2 O 2 hydrogen peroxide C 2 H 6 O ethanol, drinkable C 2 H 6 O 2 ethylene glycol, poisonous

10 How can we tell the difference between an element and a compound?

11 Classifying Matter by Physical State Matter can be classified as solid, liquid, or gas based on the characteristics it exhibits. fixed = keeps shape when placed in a container indefinite = takes the shape of the container

12 Classifying Matter by Composition Another way to classify matter is to examine its composition. Composition includes: types of particles arrangement of the particles attractions and attachments between the particles

13

14 Classification of Matter by Composition 1) made of one type of particle 2) All samples show the same intensive properties. 1) made of multiple types of particles 2) Samples may show different intensive properties.

15 Classification of Pure Substances 1) made of one type of atom 1) made of one type of molecule, or array of ions 2) units contain two or more different kinds of atoms

16 Classification of Mixtures

17 Classification of Mixtures - Homogeneous Homogeneous = mixture that has uniform composition throughout Every piece of a sample has identical characteristics, though another sample with the same components may have different characteristics. atoms or molecules mixed uniformly

18 Classification of Mixtures - Heterogeneous Heterogeneous = mixture that does not have uniform composition throughout contains regions within the sample with different characteristics atoms or molecules not mixed uniformly

19 Classification of Mixtures 1) made of multiple substances, whose presence can be seen 2) Portions of a sample have different composition and properties. 1) made of multiple substances, but appears to be one substance 2) All portions of an individual sample have the same composition and properties.

20 IMPORTANT!! Compounds CHEMICALLY COMBINED Mixtures PHYSICALLY MIXED

21 Properties of Matter

22 Properties of Matter Physical properties are the characteristics of matter that can be changed without changing its composition. Characteristics that are directly observable Chemical properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy. Characteristics that describe the behavior of matter

23 Properties of Matter Describe things by PROPERTIES PROPERTIES = stuff ABOUT stuff 2 types of properties: 1. Physical Properties = Things like size, shape, color, mass 2. Chemical Properties = Reactivity, polarity, etc.

24 Properties of Matter 2 Types of Physical Properties: 1. Intensive 2. Extensive INTENSIVE Does NOT CHANGE with amount of sample. Examples: smell, color EXTENSIVE DOES CHANGE with amount of sample Examples: How heavy, how large

25 Properties of Matter Changes to matter are either physical or chemical. Physical changes change the PHYSICAL properties of matter. Chemical changes are based on the CHEMICAL properties of matter. CHEMICAL PROPERTY: describes a substance s ability to participate and change in a chemical reaction.

26 How can we tell matter has changed?

27 Changes in Matter Changes that alter the state or appearance of the matter without altering the composition are called physical changes. Changes that alter the composition of the matter are called chemical changes. During the chemical change, the atoms that are present rearrange into new molecules, but all of the original atoms are still present.

28 Physical Changes in Matter

29 Common Physical Changes processes that cause changes in the matter that do not change its composition State Changes boiling/condensing melting/freezing subliming Subliming of Dry Ice Dry Ice CO2(g) CO2 (s)

30 Common Physical Changes C 12 H 22 O 11 (s) Dissolving of Sugar C 12 H 22 O 11 (aq)

31 Chemical Changes in Matter The rusting of iron is a chemical change. The iron atoms in the nail combine with oxygen atoms from O 2 in the air to make a new substance, rust, with a different composition.

32 Common Chemical Changes processes that cause changes in the matter that change its composition rusting processes that release lots of energy burning C 3 H 8 (g) + 5 O 2 (g) 3 CO 2 (g) + 4 H 2 O(l)

33 Evidence of Chemical Changes

34 Chemical or Physical? Determine whether each change is chemical or physical. 1. The evaporation of rubbing alcohol 2. The burning of lamp oil 3. The bleaching of hair with hydrogen peroxide 4. The forming of frost on a cold night 5. The burning of a candle 6. The melting of ice