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Matter and Energy

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Title: Matter and Energy


1
Matter and Energy
2
What is the relationship between matter, mass,
and weight?
  • Matter anything that has mass and volume (takes
    up space)
  • Mass the amount of matter in an object
  • Weight the amount of matter in an object
    including the effect of gravity on the matter
  • Measured in grams or kilograms
  • Weight is measured with a scale
  • Mass is measured with a balance
  • Mass and weight are not the same

3
Vocabulary
  • Volume the amount of space an object takes up
  • Atoms the basic building block of matter the
    smallest particle of an element that has the same
    properties as that element
  • Molecules a neutral group of atoms held
    together by chemical bonds

4
Matter can be described by its chemical and
physical properties
  • Physical Properties - Characteristics that can be
    observed or measured without changing the
    composition of matter
  • Color, mass, volume, texture, state, anything
    that can be measured with an instrument
  • Chemical Properties - Characteristics that can be
    observed only when substances interact with one
    another
  • Flammability, reactivity with acid

5
Matter changes through physical and chemical
changes
  • Physical Changes - Any change in matter that does
    not change its identity
  • Change in size, changes in state
  • Chemical Changes - Any change in matter in which
    its identity is changed
  • Burning, tarnishing, evolution of heat or gas

6
What is energy?
  • The ability to do work
  • Is measured in joules (J)
  • Two types of energy (on the atomic level)
  • Potential
  • Kinetic
  • Energy cannot be transformed from one type to
    another without any loss

7
What is potential energy?
  • Stored energy

8
What is kinetic energy?
  • Energy of motion

9
What is the Law of Conservation of Energy?
  • Energy in any closed system is neither created
    nor destroyed
  • Mass can be described in terms of energy by using
    Einsteins equation, E mc2
  • E energy, m mass, c velocity of light (3.0
    x 108 m/s)

10
What are endothermic and exothermic?
  • Exothermic energy is released into the
    surroundings, and the object feels warm (giving
    off heat)
  • Endothermic energy is absorbed from the
    surroundings, and the object feels cool
    (absorbing heat)

11
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12
What is the difference between a mixture and a
pure substance?
  • Pure substance matter composed of only one kind
    of atom or molecule (element or compound)
  • Mixture a physical combination of two or more
    pure substances

13
What is the difference between elements and
compounds?
  • Element the simplest pure substance formed of
    a single kind of atom
  • There are 117 known elements Allotropes
    different molecular forms of an element in the
    same physical state
  • Examples graphite, diamond and bucky balls

14
Elements
Sulfur
Copper
15
Allotropes of carbon
Other elements that have allotropes include
phosphorus (white, red and black), sulfur
(plastic, molecular, rhombic and monoclinic), and
oxygen (ozone, tetraoxygen)
16
What are compounds?
  • Pure substances composed of two or more different
    elements joined together chemically
  • Possess different physical and chemical
    properties from the parent elements
  • Examples salt from Na and Cl water from H2 and
    O2
  • Have a definite composition by mass of their
    combining elements

17
Compounds
Sugar made of hydrogen, oxygen and carbon
Water made of hydrogen and oxygen
18
What are the two different categories of mixtures?
  • Homogeneous a mixture containing substances
    that are uniformly distributed (same throughout)
  • Milk, tea, sodas, gold and silver jewelry,
    whipped cream, Kool-Aid, etc.
  • Heterogeneous a mixture containing substances
    that are not uniformly distributed (not same
    throughout)
  • Cereal, hamburgers, concrete, pepper, etc.

19
Sand
Muddy Water
20
How can mixtures be separated?
  • Six different methods
  • Filtration separating using a filter
  • Evaporation extra moisture is evaporated from
    the mixture
  • Centrifuge spinning a mixture centrifugal
    force pushes dense matter outward
  • Decant pouring off liquids and leaving solid
    behind
  • Distillation separation using different boiling
    points
  • Chromatography separation using a stationary
    and a mobile phase

21
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23
What is density?
  • Mass per unit volume. Physical property that
    describes how much stuff can be put into a
    space.
  • Example feathers are not dense, but lead is
    very dense
  • Formula mass/volume
  • Density Mass
  • Volume (mL or cm3)

24
How are density problems solved?
  • The volume of a sample of water is measured to be
    10.5 ml, and its mass is measured to be 9.98 g.
    What is its density?

25
How are density problems solved?
  • A substance has a density of 2.70 g/cm3. If a
    sample has a volume of 3.0 cm3, what will its
    mass be?

26
How are density problems solved?
  • A substance has a density of 3.251 g/cm3. What
    would be the volume of a 10.00 g sample of this
    substance?

27
Law of Definite (Constant) Composition
  • In a given compound, the relative numbers and
    kinds of atoms are constant
  • Example Water is 11.2 hydrogen and 88.8
    oxygen (by mass, not volume) regardless of how
    much water you have.

28
Law of Conservation of Mass
  • The total mass of materials present after a
    chemical reaction is the same as the total mass
    before the reaction.
  • For example, if 200 g of compound A react with 16
    g of compound B, the product, AB, will have a
    mass of
  • 200 g 16 g 216 g.
  • A B AB

29
Law of Multiple Proportions
  • If two elements, A and B, combine to form more
    than one compound, the masses of B that can
    combine with a given mass of A are in the ratio
    of small whole numbers.
  • For example, H2O, 16.0 g of O react with 2.0 g of
    H. In H2O2, 32.0 g of O react with 2.0 g of H.
    The ratio of O in H2O2 to O in H2O is 32.0 g/
    16.0 g 2
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