Matter and Energy

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Chemistry
Chapter 3
updated 6 years ago by chaneasegarvey
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1

Matter

  • anything that has mass and occupies space
  • makes up all things we use
2

Pure Substance

  • matter that has a fixed or definite composition
  • two kinds of pure substances:
    1. elements
    2. Compounds
3

Compounds

  • consists of two or more elements always combined in the same proportion
  • atoms are held together by bonds
  • Ex: a molecule of the compound water has two hydrogen atoms for every one oxygen atom (H2O)
4

Elements

  • simplest type of pure substance
  • composed only of one type of atoms
  • composed of atoms
  • Ex: silver is made up of silver atoms; aluminum is made up of aluminum atoms; iron of iron atoms
5

Atoms

  • tiny particles that make up each part of matter
6

Mixtures

  • type of matter that consists of two or more substances that are physically mixed but not chemically combined
  • can be separated by physical methods
  • Ex: the air we breathe is a mixture of oxygen and nitrogenous gases
  • Types of Mixtures:
    1. heterogenous mixtures
    2. homogenous mixtures
7

Homogenous Mixtures (aka solution)

  • the composition is uniform throughout the sample
  • the different parts of the mixture cannot be seen
  • Ex: air and saltwater
8

Heterogenous Mixtures

  • components do not have a uniform composition throughout the sample
  • the different parts of the mixture are visible
  • Ex: mixture of oil and water, cookies with raisins, pulp in orange juice
9

States of Matter

  • three physical forms of matter:
    1. solid
    2. liquid
    3. gas
10

Solids

  • has a definite shape and volume
  • particles are close together
  • particles move very slowly in fixed positions
11

Liquids

  • has a definite volume but not definite shape
  • same shape as its container
  • particles are close together but mobile
  • particles move slowly
12

Gases

  • does not have definite shape or volume
  • particles are far apart
  • particles move at fast speeds
  • takes the shape and volume of their container
13

Physical Properties

  • characteristics observed or measured without affecting the identity of a substance
  • includes:
    • shape
    • physical state
    • boiling and freezing points
    • density
    • color
14

Physical Properties of Copper

  • reddish-orange color
  • shiny
  • excellent conductor of heat and electricity
  • solid at 25 ℃
  • melting point 1083 ℃
  • boiling point 2567 ℃
15

Physical Change

  • when a substances physical properties change but its composition remains the same
16

Chemical Properties

  • describes the ability of a substance to change into a new substance
17

Chemical Change

  • the original substance is converted into one or more new substances (which have different physical and chemical properties)
18

Temperature

  • the measure of how hot or cold an object is compared to another object
  • indicates the heat flow from the object with a higher temperature to the object with a lower temperature
  • measured using a thermometer
19

Temperature Scales

  • Fahrenheit, Celsius, and Kelvin
  • have reference points for the boiling and freezing points
20

What is the temperature at which water freezes?

  1. 0 ℉
  2. 0 ℃
  3. 0 K

0 ℃

21

What is the temperature at which water boils?

  1. 100 ℉
  2. 32 ℉
  3. 373 K

373 K

22

How many Celsius units are between the boiling and freezing of water?

  1. 100
  2. 180
  3. 273

100

23

Fahrenheit and Celsius Scales

  • the temperature difference between freezing and boiling is divided into smaller units called degrees
  • 180 degrees Fahrenheit = 100 degrees Celsius
  • 1 ℃ = 1.8 ℉
24

Kelvin Temperature Scale

  • units called Kelvins
  • no degree symbol is used
  • has no negative temperatures
  • has the same units as celsius
  • 1 K = 1 ℃
  • Temperature Equation to Obtain Kelvins:
    • TK = Tc + 273
25

Energy

  • the ability to do work
  • makes objects move or stop
  • 2 classifications:
    1. kinetic energy
    2. potential energy
  • measured in:
    • joule (J)
    • kilojoules (kJ)... 1000 joules
    • calories (cal)
    • kilocalories (kcal)
26

Kinetic Energy

  • the energy of motion
  • any object that is moving has kinetic energy
27

Potential Energy

  • energy stored for later use
  • determined by the position of an object or by the chemical composition of a substance
28

Heat

  • the energy associated with the motion of particles
29

Calories

  • the amount of energy needed to raise the temperature if 1 g of water by 1 ℃
  • 1 cal = 4.184 J
  • 1000 cal = 1 kcal
30

Joules

  • 1000 J = 1 kJ
31

Calorimeter

  • a steel container filled with oxygen and a measured amount of water
  • used to determine food's energy value
  • indicates the heat gained by water, which is the heat lost by a sample during combustion
  • the burning of a food sample increases the temperature of water, which is used to calculate the energy value of the food
32

Specific Heat

  • the amount of heat needed to raise the temperature of exactly 1 g of a substance by exactly 1 ℃
  • different for different substances
  • T (delta T)
  • has units of J/g ℃ in the SI system and of cal/g ℃ in the metric system
33

Calculations Using Specific Heat

  • calculate the heat lost or gained by measuring its mass and temperature change