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Matter and Energy
Chapter 3
Matter
• Anything that has mass and takes up space
• Two categories
• Pure substances
• Mixtures
Pure Substances
• Matter with a fixed composition
• Either an element or compound
• Element - only one type of atom
• Compound - two or more elements
chemically combined
Mixtures
• Two or more different substances are
physically mixed
• Can vary the composition
• Two types
• Homogeneous
• Heterogeneous
Classification of Matter
Classification of Matter
Practice
1. Classify as a mixture or pure substance:
a. soft drink
b. propane [C3H8]
c. cheese sandwich
d. iron [Fe] nail
e. salt substitute [KCl]
Classification of Matter
Practice
2. Classify each of the following mixtures as
homogeneous or heterogeneous:
a. nonfat milk
b. chocolate-chip ice cream
c. gasoline
d. peanut butter sandwich
e. cranberry juice
States of Matter
1. Solid
2. Liquid
3. Gas
Physical Properties and
Changes
• Physical property
• Characteristics that can be observed or
measured without affecting the identity
• Examples:
• Physical change
• State or appearance changes, but the
composition does not
• Examples:
Chemical Properties and
Changes
• Chemical property
• Describe the ability of a substance to
change into a new substance
• Examples:
• Chemical change
• Original substance is changed into new
substance
• Examples:
Properties of Matter Practice
1. Describe each of the following properties as
physical or chemical:
a. neon is a color gas at room temperature
b. apple slices turn brown when exposed to air
c. phosphorus will ignite when exposed to air
d. at room temperature, mercury is a liquid
e. propane gas is compressed to a liquid for
placement in small cylinder.
HOMEWORK
page 74 3.1, 3.3, 3.5
page 78 3.7, 3.9, 3.11, 3.13
Temperature
•
Temperature Conversions
• TF = 1.8(TC) + 32
• Tc = (TF - 32) / 1.8
• TK = TC + 273
Temperature Practice
1. Make the following temperature
conversions:
a. 37.0oC to oF
b. -27oC to K
c. 15oF to oC
d. 65.3oF to oC
e. 224 K to oC
Energy
• Ability to do work
• Classified as:
• Kinetic energy
• Potential energy
Heat
• Energy associated with the motion of particles
• Flows from object with higher temperature to
object with lower temperature
• Units
• Joule (J)
• calorie (cal)
• 1 cal = 4.184 J
HOMEWORK
page 82 3.17
page 85 3.23, 3.27
Lab 3 Pre-Lab
Specific Heat
• All substances have own ability to absorb
heat
• Definition: amount of heat required to
change the temperature of exactly 1 g of the
substance by exactly 1oC
Heat Equation
Specific Heat Practice
1. Determine the amount of energy, in joules,
required to heat 25.0 g of water from 12.5oC
to 25.7oC. The specific heat of water is 4.184
J/goC.
Specific Heat Practice
2. Calculate the specific heat for tin if a 18.5 g
sample of the element absorbs 183 J as it
increases in temperature from 35.0oC to
78.6oC.
Specific Heat Practice
3. Calculate the change in temperature for 115
g of copper that loses 2.45 kJ. The specific
heat of copper is 0.385 J/goC
HOMEWORK
page 90
3.31, 3.33, 3.37, 3.41
Atoms and Elements
Chapter 4
The Periodic Table
The Periodic Table
• Family/Group
• Vertical column
• Elements in a family have similar chemical
properties
• Period
• Horizontal row
• Physical and chemical properties change
somewhat regularly across a period.
The Periodic Table
• Names of Different Groups:
• Group 1: Alkali Metals
• Group 2: Alkaline Earth Metals
• Group 17: Halogens
• Group 18: Noble Gases
• Groups 1-2, 13-18: Representative Elements
• Groups 3-12: Transition Metals
The Periodic Table
•Types of Elements
•Metals
• Mostly shiny solids [Hg is only liquid]
• Good conductors of heat/electricity
• Ductile and Malleable
• Left side of periodic table
The Periodic Table
• Types of Elements [cont’d]
• Nonmetals
• Dull in appearance
• Not conductive
• Low melting points
• Low densities
• Right side
• Metalloids
• Characteristics of both
• Zigzag down middle – B, Si, Ge, As, Sb, Te, Po, At
HOMEWORK
page 114 4.7, 4.9, 4.13
The History of the Atom
• Aristotle vs Democritus - 500 BC
The History of the Atom
• John Dalton – 1808
• Atomic Theory
• All matter is composed of tiny particles
called atoms
• All atoms of a given element are the same; atoms
of different elements are different
• Atoms of two or more elements combine to form
compounds
• A chemical reaction involves the rearrangement,
separation or combination of atoms
Modern Atomic Theory
• Not all aspects of Dalton’s theory have proven to
be correct.
• Atoms are divisible into smaller particles.
• A given element can have atoms with different
masses
• Some remain unchanged:
• All matter is composed of atoms.
• Atoms of any one element differ in properties
from atoms of another element.
Structure of the Atom
● Atom
● Smallest part of an element that retains
the chemical properties of that element.
● Two regions:
1. The nucleus: a very small region located at
the center of the atom
2. The large region surrounding the nucleus
Subatomic Particles
● Electron
● Negatively charged
● In the region surrounding the nucleus
● Proton
● Positively charged
● In the nucleus
● Neutrons
● Neutral charge
● In the nucleus
Discovery of the Electron
• J.J. Thomson – 1897
• Studied cathode rays
• Called the particles electrons
• Measured charge to mass ratio
of an electron
• Plum pudding model of the
atom
Discovery of the Nucleus
• Ernest Rutherford - 1911
• Gold Foil Experiment
• Shot alpha particles at thin gold foil
• Results
• Most passed through
• Some deflected at sharp angles
• Conclusions
• Atom mostly empty space
• Nucleus - dense, small, positive
Mass of the Atom
• Atoms are so small, scientists use a unit called
atomic mass unit to talk about their masses
• 1 amu = 1.66 x 10-24 g
HOMEWORK
Atomic Number
▪ Specific for each
element
▪ Same for all atoms of
an element
▪ Equal to the number of
protons in an atom
Mass Number
•Represents the number of subatomic
particles in the nucleus
•Equal to the sum of protons and neutrons
•Not found on the periodic table
Atomic Number and Mass
Number Practice
1. An atom of zinc has a mass number of 65.
a.
b.
c.
How many protons are in a zinc atom?
How many neutrons are in a zinc atom?
What is the mass number of a zinc atom that
has 37 neutrons?
2. An atom has 14 protons and 20 neutrons.
a.
b.
c.
What is its atomic number?
What is its mass number?
What is this element?
Isotopes
• Atoms of the same element that have different
masses
• Have same number of protons
• Differ in number of neutrons
Isotopes
• Hyphen notation
– Mass number is written after the name of the
element
– Hydrogen-3
– Carbon-14
– Oxygen-18
• Nuclear symbol
– Superscript is the mass number; subscript is
the atomic number
Isotopes Practice
1. What are the number of protons, neutrons, and
electrons in the following isotopes? Then give
the symbol notation each.
a. strontium-89
b. chromium-52
c. sulfur-34
d. bromine-81
HOMEWORK
Giant chart
Average Atomic Mass
▪ Gives the mass of an “average” atom of
each element compared to C-12.
▪ Not the same as the mass number.
▪ Calculated using a weighted average.
Average Atomic Mass
Average Atomic Mass
•Average Atomic Mass Equation:
Avg mass = (abundance of isotope 1) x (mass of isotope 1)
+ (abundance of isotope 2) x (mass of isotope 2)+ …
Average Atomic Mass
Examples
1. The atomic mass of chlorine is 35.45 amu.
Based on this information, which of the
isotope of chlorine is more abundant chlorine-35 or chlorine-37?
Average Atomic Mass
Examples
2. Copper consists of 69.15% copper-63, which has
an atomic mass of 62.929 601 amu, and 30.85%
copper-65, which has an atomic mass of 64.927
794 amu. Calculate the average atomic mass of
Copper to two decimal places.
Average Atomic Mass
Examples
3. Three isotopes of argon occur in nature.
Calculate the average atomic mass of argon to
two decimal places, given the following relative
atomic masses and abundances of each of the
isotopes: argon-36 (35.97 amu; 0.337%), argon-38
(37.96 amu; 0.063%), and argon-40 (39.96 amu;
99.600%).
HOMEWORK
page 125 4.33, 4.35, 4.40, 4.41, 4.42, 4.43, 4.44