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Bellwork

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Bellwork Which of the following represents a mixture? a piece of copper wire oxygen in a pressurized tank a slice of mushroom pizza a lead fishing weight – PowerPoint PPT presentation

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Title: Bellwork


1
Bellwork
  • Which of the following
  • represents a mixture?
  • a piece of copper wire
  • oxygen in a pressurized tank
  • a slice of mushroom pizza
  • a lead fishing weight

2
Chapter 13 Review
  • Matter anything that has mass and takes up
    space
  • Mass the amount of matter in something
  • Volume the amount of space something occupies
  • Which of the following is matter?
  • A car?
  • A box?
  • You?

3
What is a property?
  • A Property is a characteristic of a substance
    that can be observed.

4
Physical Property
A physical property is one that can be observed
without changing the identity of the substance.
5
Examples
  • Malleability the ability to be hammered into a
    thin sheet
  • Ductility the ability to be stretched into a
    wire
  • Melting/freezing point
  • Boiling point
  • Density
  • Solubility
  • Specific heat the amount of heat required to
    heat a substance 1 degree Celsius
  • Luster shiny, matt

6
Special Physical Properties
  • Melting point the temperature at which a
    substance changes from a solid to a liquid at a
    given pressure
  • water 0oC
  • Boiling point the temperature at which a
    substance changes from a liquid to a gas at a
    given pressure
  • water 100oC

7
Density
  • Density is the amount of mass per unit of volume.
  • Like many other properties it can be used to
    identify a substance.
  • The density of water is 1.0g/mL

8
Calculating Density
  • D m/V g/mL g/cm3
  • Ex A cube has a mass of 2.8 g and occupies a
    volume of 3.67 ml. Would this object float or
    sink in water?
  • Mass 2.8 g Volume 3.67 mL
  • D 2.8g/3.67 mL 0.76 g/mL

9
Identification by Density
  • A liquid has a mass of 25.6 g and a volume of
    31.6 mL.
  • Use the table below to identify the substance.

M25.6 g V31.6 mL D 25.6 g/31.6 mL
D 0.81 g/mL The substance is ethanol.
10
Chemical Properties
  • A Chemical property is a property that can
    only be observed by changing the identity of the
    substance
  • Examples
  • flammability
  • ability to rust
  • reactivity with vinegar

11
Element
  • An element is a pure substance that cannot be
    broken down into any other substance by chemical
    or physical means.
  • Examples
  • aluminum
  • zinc
  • oxygen

12
Atom
  • Elements are comprised of atoms, which are so
    small they cannot be seen even with a microscope.

13
Molecule
  • Atoms bond together chemically to form
    molecules.

14
Compound
  • A compound is a pure substance made of 2 or
    more elements chemically combined in a set ratio.
    Compounds cannot be easily separated.

15
Mixture
  • A mixture is a pure substance made of 2 or
    more elements, compounds, or both, that are
    together yet not chemically bonded and therefore
    can be separated by physical means.

Heterogeneous Homogeneous
16
Changes
  • Physical change substance maintains its
    chemical makeup
  • Ex state changes, dissolving
  • Chemical change substance becomes something else
    entirely
  • Ex burning, oxidation

17
Chemical Reactions
  • Endothermic reactions must absorb heat/energy in
    order for the reaction to take place.
  • This intake of energy may be observed as a
    decrease in temperature as the reaction proceeds.
  • Exothermic reactions release heat from the
    reaction.

18
Chemical Reactions
  • Reactants are the chemicals that go into a
    reaction.
  • Products are the chemicals products that are
    created by the reaction.

19
Law of Conservation of Matter
  • States that the
  • Mass of the reactants
  • Mass of the Products
  • (in a closed system)
  • Ex 5 g of sodium(Na) 5 g of chloride (Cl)
    yields 10g of table salt (NaCl)

20
Conservation of Matter Lab
  • Objective
  • To demonstrate the Law of Conservation of
    Matter by reacting vinegar baking soda in a
    closed system.

21
Bellwork
  • What is the difference between a compound
    and a mixture?

22
Venn Diagram
23
  • ENERGY!

24
2 Main Types of Energy
25
Temperature Energy
26
Temperature
27
Law of Conservation of Matter
  • States that the
  • Mass of the reactants
  • Mass of the Products
  • Also stated as matter cannot be created nor
    destroyed only transformed.

28
Law of Conservation of Energy
  • Energy also cannot be created nor destroyed
    only transformed or transferred.

29
Law of Conservation of Energy
30
Exothermic
Produces Heat
31
Endothermic
Soaks up heat from the surroundings observed
as a decrease in temperature
25 ml citric acid soln 15 g baking soda
32
Bellwork
  • Which pure substance is composed of more
    than one element?
  • - carbon
  • - gold
  • - water
  • - sodium

33
Intro.
  • The PERIODIC TABLE contains information about
    the different ELEMENTS that make up all the
    solids, liquids, and gases in the known universe.

34
Natural vs. Synthetic
  • The majority of the known elements are
    naturally occurring, however all elements above
    92, are known as SYNTHETIC elements having been
    created in a lab.

35
Atoms
  • Elements are one or more identical ATOMS and
    each element has its own unique atom that looks
    different than all the other elements.

36
Organization
  • Elements are organized on the periodic table
    by their ATOMIC NUMBER, which is the number of
    PROTONS in the nucleus.

37
Isotopes
  • Atoms of the same element can have different
    numbers of NEUTRONS the different possible
    versions of which are called ISOTOPES.

38
Calculate of Neutrons
  • To determine the average number of neutrons
    in an element Round the atomic mass to the
    nearest whole number and subtract the atomic
    number (of protons). Ex K 39 19 20 neutrons.

39
Atomic Mass
  • The ATOMIC MASS listed on the periodic table
    is an average of the mass of all known isotopes
    of that element.

40
Symbols
  • Hg Mercury
  • Au Gold Pb Lead
  • Sn Tin Ag Silver
  • Cu Copper Fe Iron
  • K Potassium Na - Sodium

41
Patterns in the Table
  • The PROPERTIES of an element can be
    predicted by their location on the periodic table.

42
Group 1
  • Alkali Metals do not occur uncombined in
    nature highly chemically reactive

43
Group 2
  • Alkaline Earth Metals also do not occur
    uncombined good conductors

44
Groups 3-12
  • Transition Metals also good conductors
    form colorful compounds that last a long time
    since they are not highly chemically reactive

45
Lanthanides
  • Soft, shiny, malleable metals with high
    conductivity

46
Actinides
  • Most are synthetic and the nuclei are
    unstable (meaning they break apart quickly)

47
Metalloids
  • Along the stair step line
  • (7) METALLOIDS that have properties of
    metals and non-metals are very useful for their
    varying abilities to conduct electricity (i.e.
    silicon semi-conductors in computer chips).

48
Non-Metals
  • The NON-METALS are not good conductors but
    they combine with others readily to form
    compounds.
  • Many of these elements are crucial in
    creating and maintaining life (C, N, O, P, S).

49
Group 17
  • HALOGENS - meaning salt forming
  • They are DIATOMIC, meaning they never exist
    as a single atom.

50
Group 18
  • NOBLE GASES do not bond with other
    elements at all, hence why they are called noble

51
Bellwork
  • The element silicon is best used for which
    purpose?
  • - as a container to keep coffee hot
  • - as a semiconductor in a computer chip
  • - as a material to make airplane frames
  • - as a malleable material for coins and
    jewelry

52
Protons Electrons
  • Atoms are in general NEUTRAL since they
    generally have the same number of protons as
    electrons in their pure form. They strive at all
    times to maintain their neutrality.

53
Electrons
  • We know already that ELECTRONS are orbiting
    around the nucleus of the atom. Where they are
    orbiting helps us to make some predictions about
    how and if an element will combine with other
    elements (reactivity).

54
Energy Levels
  • There are several ENERGY LEVELS within the
    electron cloud and each can only hold a certain
    number of electrons.
  • The period/row on which an element can be
    found will tell you how many energy levels there
    are in an atom of that element.

55
Filling the Energy Levels
  • 1st energy level holds 2 electrons
  • 2nd energy level holds 8 electrons
  • 3rd energy level holds 18 electrons
  • There are 7 energy levels in total but we
    will only concern ourselves now with the first 18
    elements so we will only need to know about the
    first 3.

56
Valence Electrons
  • Not all energy levels will be filled and the
    electrons that reside in the outermost energy
    level are called the VALENCE ELECTRONS.
  • You can find out at a glance how many
    valence electrons an element has by looking at
    the group number.

57
Bell Work
  • How can a scientist, using the periodic
    table, find an element with properties similar to
    another element?
  • - by comparing density
  • - by finding its periodic group
  • - by comparing malleability
  • - by comparing atomic weight

58
Bell Work
  • Which periodic group does the element
    chlorine belong to?
  • - alkali metals
  • - alkali earth metals
  • - noble gases
  • - halogens

59
Bell Work
  • How would you calculate the number of
    neutrons in an atom of a given element?

60
Bell Work
  • What is the NAME of the family/group that
    fluorine belongs to?

61
Bell Work
  • What is the NAME of the family/group that
    Potassium belongs to?
  • Dont forget to have your completed Periodic
    Table from yesterday out when I come around with
    the stamp ?

62
Bell Work
  • Which of the following correctly
    compares the elements on the right side of the
    periodic table with the elements on the left?
  • - The elements on the right side are generally
    denser than the elements on the left side.
  • - The elements on the left side are better
    conductors of electricity than the elements on
    the right side.
  • - The elements on the right side are better
    conductors of thermal energy than those on the
    left side.
  • - The elements on the left side have lower
    melting point than the elements on the right
    side.
  • Dont forget to have your completed homework
    out?

63
Bellwork
  • Which element is LEAST likely to combine
    with another element to form a molecule?
  • Chlorine (Cl), a halogen
  • Iron (Fe), a metal
  • Neon (Ne), a noble gas
  • Silicon (Si), a metalloid

64
Molecules
  • 2 or more atoms help together by chemical
    bonds

65
Valence Electrons
  • Are the electrons on the outermost shell of
    an atom that participate in bonding.

66
Lewis Dot Structures
  • Diagrams that show electrons, bonding, and
    lone pairs of electrons.

67
Covalent Bonds
  • A chemical bond that involves the SHARING of
    their valence electrons.

68
Ionic Bonds
  • A bond that involves the TRANSFER of valence
    electrons from one atom to another.

69
Ions
  • Atoms that gain or lose electrons, therefore
    having a charge.

70
Cations
  • Atoms with a positive charge. These are
    metals since they lose electrons because they
    have one or 2 to spare.

71
Anions -
  • Atoms with a negative charge. These are
    nonmetals since they gain electrons because they
    only need 1 or 2 to become stable.

72
Ionizing Energy
  • The amount of energy required to remove an
    electron from an atom.

73
Bellwork
  • What do these chemicals have in common?
  • Cu SO4 ZnCl4 Fe2O3
  • Number of atoms
  • Presence of oxygen
  • Presence of metal
  • Number of bonds

74
Bellwork
  • You have a sample of an unknown element.
    At room temperature, this element is a gas
    reacts easily with other elements to form
    compounds. In which column of the periodic table
    does this element most likely belong?
  • - IIA
  • - VA
  • - VIIA
  • - VIIIA

75
Chemical Reactions
  • Chemical change occurs when bonds break and
    new bonds are formed.
  • The chemical composition (makeup) of the
    substance(s) has been altered.

76
Evidence of Chemical Change
  • Change of properties
  • heat absorbed -endothermic
  • heat released exothermic
  • gas formation (O2, CO2)
  • Precipitate formation

77
Chemical Equations
  • Reactants ? Products
  • 2H2 O2 ? 2H20
  • Coefficient of molecules
  • Subscript - of atoms

78
Types of Chemical Reactions
  • Synthesis
  • A B ? C
  • Decomposition
  • C ? A B
  • Replacement
  • AB CD ? AD BC

79
Conservation of Mass
  • Mass of Reactants
  • Mass of Products

Remember the lab where we reacted baking soda and
vinegar and trapped the CO2 in the balloon!
80
BellWork
  • Five molecules of methane contain five carbon
    atoms and 20 hydrogen atoms. What is the
    chemical formula of methane?
  • CH4
  • C2H8
  • C4H20
  • C5H20

81
Activation Energy
  • Activation Energy is the minimum amount of energy
    required to start a chemical reaction.
  • It has a cascading effect.
  • An endothermic reaction requires A LOT of
    activation energy.

82
Surface Area
  • If you break the reactants into smaller pieces
    then there is more surface area in contact with
    the other reactant. Thereby increasing the
    chance that 2 oppositely charged atoms can bond
    together.

83
Temperature
  • If you increase the temperature then the
    molecules are moving faster and thereby making
    connections more frequently.

84
Concentration
  • Concentration is the amount of a substance in a
    given volume. Increasing the concentration of a
    substance means there are more atoms or molecules
    available for bonding.

85
Catalysts
  • Catalysts increase the rate of reaction by
    lowering the activation energy required to start
    the reaction.
  • They are not reactants and they are not consumed
    during a reaction.

86
Inhibitors
  • Inhibitors slow reactions by interfering with the
    reactants ability to get to each other.

87
Demo Time
  • Decomposition of Hydrogen Peroxide
  • KI
  • 2H2O2 ? 2H2O O2

88
Follow Up Questions
  • Answer on a sheet of notebook paper
  • Describe what happened in this demonstration.
  • Is this an endothermic or exothermic reaction?
  • What is a catalyst?
  • Name the catalyst in this demonstration.
  • Could it be included as a reactant in the
    chemical equation?

89
Acids
  • Produce H ions in H2O
  • Ex HCl ? H Cl-
  • Properties
  • Tastes sour
  • Corrosive reaction w/metal
  • Reacts w/CO32- to make CO2
  • Turns blue litmus paper red

90
Examples of Acids
  • HCl hydrochloric acid
  • CH3CO2H acetic acid (vinegar)
  • H2SO4 sulfuric acid
  • Ascorbic Acid Vitamin C (citrus)
  • Fertilizers
  • Nitric Phosphoric Acid
  • Lactic Acid

91
Bases
  • Produce OH- ions in H2O
  • Ex NH3 H2O ? NH4 OH-
  • Tastes bitter
  • feels slippery
  • Turns red litmus paper blue

92
Examples of Bases
  • NaHCO3 baking soda
  • household cleaners including
  • NH3- ammonia
  • Drain Cleaner

93
Strength
  • The strength of an acid or a base is based on how
    well it produces ions in water.
  • Strong Acids HCl H2SO4
  • Strong Bases - NaOH

94
Measuring Strength
  • pH Potential Hydrogen
  • Range of values from 0 to 14 that describes the
    concentration of H ions in a substance.
  • Since we are measuring H ions and they are
    produced by acids, we can expect the higher it is
    on the scale, the more acidic it is!

95


96
Safety
  • Know the pH (strength) of the acid or base you
    are handling.
  • Everything from 2-11 is in the safe zone.

97
Precautions
  • When working with a strong acid or base (0-2 or
    11-14) be sure to wear goggleseven if its a
    dilute solution!
  • For spills-
  • Pour vinegar on a base sodium bicarbonate on an
    acidbecause

98
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99
Acid Base Neutralization
  • Displacement reaction
  • Acid Base ?
  • (liquid) water (solid) salt
  • Salt Group 1-2 Metal a halogen

100
Demo Time
NaHCO3 NaOH ? Na2CO3 H2O
101
Precipitate Reactions
  • If the ions in 2 solutions combine to form a
    solid and that solid is NOT soluble with the
    solvent produced a precipitate will form.
  • ? Example
  • Fe(NO3)3(aq) 3 NaOH(aq) ? Fe(OH)3(s) 3
    NaNO3(aq)

102
Demo Time
  • Cu(NO3)2(aq) 2 NaOH(aq) ? Cu(OH)2(s) 2
    NaNO3(aq)
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