The Properties of Matter 1

2 Properties Distinguish Matter Each sample of matter is distinguished by its characteristics. The characteristics of a substance are called its properties. Some properties of matter can be observed directly. Other properties of matter are observed when it changes its composition.

3 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.

4 Some Physical Properties

5 Some Physical Properties of Iron Iron is a silvery solid at room temperature with a metallic taste and smooth texture. Iron melts at 1538 °C and boils at 4428 °C. Iron’s density is 7.87 g/cm 3. Iron can be magnetized. Iron conducts electricity, but not as well as most other common metals. Elemental Iron

6 Some Chemical Properties

7 Some Chemical Properties of Iron Iron is easily oxidized in moist air to form rust. When iron is added to hydrochloric acid, it produces a solution of iron(II) chloride and hydrogen gas. Iron is more reactive than silver, but less reactive than magnesium.

8 Practice—Decide Whether Each of the Observations About Table Salt Is a Physical or Chemical Property Salt is a white, granular solid. Salt melts at 801 °C. Salt is stable at room temperature, it does not decompose. 36 g of salt will dissolve in 100 g of water. Salt solutions and molten salt conduct electricity. When a clear, colorless solution of silver nitrate is added to a salt solution, a white solid forms. When electricity is passed through molten salt, a gray metal forms at one terminal and a yellow-green gas at the other.

9 Practice − Decide Whether Each of the Observations About Table Salt Is a Physical or Chemical Property Salt is a white, granular solid = physical. Salt melts at 801 °C = physical. Salt decomposes into sodium metal and chlorine gas = chemical. 36 g of salt will dissolve in 100 g of water = physical. Salt solutions conduct electricity = physical. When a clear, colorless solution of silver nitrate is added to a salt solution, a new white solid forms = chemical. When electricity is passed through molten salt, a gray metal forms at one terminal and a yellow-green gas at the other = chemical.

10 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. aka as a chemical reaction.

11 Changes in Matter, Continued Physical Changes—Changes in the properties of matter that do not effect its composition. Heating water.  Raises its temperature, but it is still water. Evaporating butane from a lighter. Dissolving sugar in water.  Even though the sugar seems to disappear, it can easily be separated back into sugar and water by evaporation.

12 Phase Changes Are Physical Changes Boiling = liquid to gas. Melting = solid to liquid. Subliming = solid to gas. Freezing = liquid to solid. Condensing = gas to liquid. Deposition = gas to solid. State changes require heating or cooling the substance. Evaporation is not a simple phase change, it is a solution process.

13 Changes in Matter, Continued Chemical Changes involve a change in the properties of matter that change its composition. A chemical reaction. Rusting is iron combining with oxygen to make iron(III) oxide. Burning results in butane from a lighter to be changed into carbon dioxide and water. Silver combines with sulfur in the air to make tarnish.

14 Practice—Classify Each Change as Physical or Chemical Evaporation of rubbing alcohol. Sugar producing a black solid when heated. An egg splitting open and spilling out. Sugar fermenting. Bubbles escaping from soda. Bubbles that form when hydrogen peroxide is mixed with blood.

15 Practice—Classify Each Change as Physical or Chemical, Continued Evaporation of rubbing alcohol = physical. Sugar producing a black solid when heated = chemical. An egg splitting open and spilling out = physical. Sugar fermenting = chemical. Bubbles escaping from soda = physical. Bubbles that form when hydrogen peroxide is mixed with blood = chemical.

16 Elements Each element has a unique name and symbol. The symbol is either one or two letters  One capital letter or one capital letter + one lower case letter.  H = Hydrogen = “water-former”  Br = Bromine = ‘stench’ Liquid Bromine