Matter and Change

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Matter and Change

• What is chemistry?
• The study of what things are made of
• and the changes they undergo.

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Please do now!

• Work independently.
• Write two professions (not teaching) that use
  chemistry knowledge every day.
• Think about your daily routine. List two things
  that you do each day that involves chemistry.
• Name one thing in your life that has nothing to
  do with chemistry.

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There are five major divisions of chemistry

• organiccontaining carbon C (mostly living
  things)
• inorganicNOT containing carbon (nonliving
  things)
• analyticalcomposition of substances (what they
  are made of)
• physicalhow things behave reasons why
• biochemistryliving organisms (animal body
  functions)

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So what are their jobs?

• Pharmacists researching new cancer drugs
• Crime scene investigators (CSI) forensics
• Anthropologists how were the mummies preserved?
• Doctors investigate the processes that lead to
  liver disease
• Chefs creating new recipes

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Pure vs. Applied

• PURE
• Uncontaminated
• Knowledge for knowledge sake
• Objective just the facts

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Pure vs. Applied

• APPLIED
• Takes the scientific knowledge of pure chemistry
  and uses it to effect people or the environment.

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Thingsmatteranything that has mass or takes up
space
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Classifying Matter

• States of matter solid, liquid, gas
• Changes
• These are also called phases
• Phases of matter are solid, liquid, gas.

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States of matter

• Organized according to how particles in that
  matter behave (or move around).
• How does it move?
• Does it have shape?
• Does it have definite volume?

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SOLID

• Does not flow.
• Definite shape.
• Definite volume.

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LIQUID

• It flows.
• Takes on the shape of its container.
• Has a definite volume.

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GAS

• It flows.
• Takes on the shape of its container
• Has NO definite volume-takes on the volume of its
  container.

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Why do they behave this way?

• Amount of
• space between the particles.

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Physical properties

• alters a substance w/o changing its composition

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Types of physical properties
Extensive property depends on the AMOUNT of
matter in a substance Mass, volume Intensive
property depends on the TYPE of matter in a
substance Hardness, luster, odor
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Examples of physical properties

• color
• density
• taste
• solubility or dissolve ability
• ANY PHASE CHANGE

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Phase changes

• Are changes in state of matter
• Types of phase changes
• boil
• melt
• freeze, solidify, crystallize
• evaporate
• distill
• sublime

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More phase changes

• distillation-a liquid is boiled to produce a
  vapor which is then condensed again to a liquid
• sublimation-skips a phase-goes from solid to gas
  or vapor without becoming a liquid
• (moth balls, dry ice, air fresheners)

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Chemical properties

• how a substance reacts with something else
• Chemical equation REACTANTS ? PRODUCTS
• ? means yields

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Examples ofChemical properties

• flammability
• combustion
• neutralization
• REACTS WITH

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Physical change

• the original substance still exists, it has only
  changed in form (size, shape, phase)
• the original chemical formula is still in tact!

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Physical changes in the lab

• Words that indicate that a
• PHYSICAL CHANGE
• has taken place
• dissolve melt
• tear freeze
• grind evaporate
• cut (ALL phase changes)

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Examples of a physical change

• Iron is more dense than aluminum
• Mercury melts at -39oC
• Oil and water do not mix
• Sugar dissolves in water
• Water boils and becomes steam
• A tire is inflated with air

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Chemical change

• a new substance is produced
• results in the rearrangement of atoms
• so that new substance has a new set of
• properties eg H2O
• The original chemical formula comes apart!

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Examples of a chemical change

• Iron and oxygen form rust
• Magnesium burns brightly when ignited
• Milk sours
• HCl reacts with KOH to produce salt, water and
  heat

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Chemical changes in the lab

• precipitate forms
• gas released (bubbles)
• color change
• odor
• energy transfer occurs (exothermic or
  endothermic)
• Concept of irreversibility

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Chemical changes in the lab

• Words that indicate that a
• CHEMICAL CHANGE
• has taken place
• rot rust
• decompose ferment
• grow decay
• corrode sprout

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Energy and chemical changes

some chemical reactions absorb or give off
energy in the form of heat or light
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Energy and chemical changes

SYSTEM focus of our attention SURROUNDINGS
everything outside of the system
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Energy and chemical changes

Exothermic energy is given off by the system
to the surroundings SYSTEM SURROUNDINGS (you
feel heat) Endothermic energy is taken
into the system from the surroundings SYSTEM S
URROUNDINGS (you feel cold)
energy
energy
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Real life example

When baking soda (NaHCO3) is mixed with some
types of cookie dough, the dough is baked in a
hot oven the baking soda absorbs energy and
breaks apart into CO2, H2O, and Na2CO3. The CO2
(a gas) and H2O (in the form of steam, a gas)
puff up the cookies.
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Law of Conservation of Energy

• During any chemical or physical change, the total
  amount of energy remains THE SAME
• Energy can not be created or destroyed
• Energy is transferred but never lost

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Heat

• energy that is transferred between objects that
  are at different temperatures
• heat always moves from warm to cold
• heat is a form of kinetic energy

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How do we measure heat?

• Use a thermometer to measure temperature which
  tells us about the average kinetic energy of the
  molecules in the substance

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Speaking of conservation

• Remember the law of conservation of____
• Mass, matter, energy
• Each is conserved or equal on both sides of the
  arrow in a chemical equation
• Total g on LEFT is equal to total g on RIGHT

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Classification of Matter
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Matter can be...

• ELEMENT located on PT cannot be separated into
  simpler substances (Fe)

• SUBSTANCE
• you can write a chemical formula for them (from
  the PT)
• cannot be easily separated (NaCl or H2O)

• COMPOUND 2 or more different elements
  chemically combined present in same ratio (H20
  and H2O2)

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Matter can be...

• HOMOGENEOUS same throughout (Hershey Bar)

• MIXTURE
• physical blend of 2 or more substances
• easily separated (salad)
• Classified by how well mixed they are!

• HETEROGENEOUS different throughout (Snickers
  Bar)

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Remember

• All solutions are mixtures

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Common solutions

• Air
• carbon dioxide and oxygen in nitrogen
• gas-gas
• Soda water
• carbon dioxide in water
• gas-liquid
• Vinegar
• acetic acid in water
• liquid-liquid

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Please do now!

• Work independently.
• Handout Matter-Substance vs. Mixture p. 17
• Is the type of matter listed a substance or a
  mixture?
• substance gt element or compound
• mixture gt hetero or homogeneous

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Mixtures are easy to separate

• Methods of separation
• Decant (pour off) oil and water
• Filtration separates a solid from a liquid -
  muddy water
• Distillation salt water
• Chromatography separation of liquids

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Please do now!

• 1. Find 3 elements whose symbol is one letter.
  What do you notice?
• 2. Find 3 elements whose symbol is two letters.
  What do you notice?
• 3. Name 3 elements whose symbol is the first two
  letters of its name.
• 4. Name 3 elements whose symbol is different from
  the first two letters of its name.
• 5. Find 2 you know are metals and 2 you know are
  gases.

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Did you notice...

• 1. All elements with single letter symbols are
  capitalized
• 2. Two letter symbols are CAPITAL then small
• 3. Aluminum Al (symbol relates to name)
• 4. Some symbols are named after Greek or Latin
  roots (p. 17 in your book) and next slide
• 5. Where are these located on your periodic
  table?

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Some examples

• Tin Sn from the Latin stannum
• Tungsten W from the Latin wolfram
• Lead Pb from the Latin plumbum
• Iron Fe from the Latin ferrum

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Metals, nonmetals, metalloids

• METALS to the left
• NONMETALS to the right
• METALLOIDS the steps (middle)

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Make your own PT

• Transitions
• Inner transitions Lanthanides/Actinides

• Metals
• Nonmetals
• Metalloids

• Alkali Metals
• Alkaline Earth Metals
• Halogens
• Noble Gases

• Blocks
• Groups

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Please do now!http//www.chemistry.org/portal/a/c
/s/1/acsdisplay.html?DOCsitetools5Cperiodic_tabl
e.html

• Color all metals blue.
• Color all nonmetals green
• Trace the steps in red then color all
  metalloids yellow (use the PT in the back of your
  text to find the steps)

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Types of atoms

• Monatomic stand alone, one type of atom
• Diatomic exist as a double (two) never found
  alone in nature
• N, O, F, Cl, Br, I, H
• The magic 7 plus one

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What is an alloy?

• Metallic mixture of two or more elements (at
  least one is a metal)
• made by melting the elements then mixing and
  cooling them
• HOMOGENEOUS

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What is an alloy?

• Some examples
• Brass copper zinc
• Bronze copper tin
• Steel several different elements

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What is an alloy?

• Advantages
• properties of alloys are often superior to those
  properties of their component elements
• STERLING SILVER-harder and more durable than pure
  silver but still soft enough to be made into
  jewelry and flatware
• BRONZE-more easily cast than its part and harder
  than copper