Introduction to Chemistry

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CHAPTER 1

• Introduction to Chemistry

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What is chemistry?

• The study of matter
• Composition
• Structure
• Properties
• Changes that matter undergoes
• Some chemicals are natural and others are
  synthetic

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Branches of Chemsitry

• 1. Organic - chemicals containing carbon
• 2. Inorganic all elements besides carbon
  mostly what we study this year

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Branches of Chemistry (cont.)

• 3. Physical chemistry studies how energy can be
  transferred into matter (Emc2)
• 4. Biochemistry studies substances and
  processes that occur in living things
• 5. Analytical chemistry- ID of materials (CSI)
  determine composition of substances quality
  control

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What is matter?

• Anything that has mass, volume, and inertia.
• Examples Which of the following are matter?
• Sand
• Light
• Paper
• O2
• Heat

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How do we categorize matter?

• 4 states of matter and their properties
• 1. solid
• 2. liquid
• 3. gas
• 4. plasma

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solid

• Definite Shape
• Definite Volume
• Stationary Particles
• Densely Packed

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liquid

• Indefinite Shape
• Definite Volume
• Particles are fluid flow

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gas

• Indefinite Shape
• Indefinite Volume (fills the container)
• Low denisty

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plasma

• Indefinite shape
• Indefinite volume
• Fast moving
• Sea of charged particles in a gas like medium

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CHEMiCAL and PHYSiCAL PROPERTiES

• What is a property?
• Characteristics that allow us to distinguish or
  identify matter.
• May be expressed QUALITATIVELY or QUANTITATIVELY.
• May be PHYSICAL or CHEMICAL.

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PHYSICAL PROPERTY

• Definition
• A property that can be observed without altering
  the substance.
• Examples size, mass, volume, melting point,
  boiling point, density, ductility, malleability,
  hardness, color, crystal like shape, solubility,
  luster, odor, taste

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CHEMICAL PROPERTY

• Definition
• A property that describes the substances ability
  to undergo a change. Cannot be observed without
  altering the substance.
• Examples reacts with, flammability, inert,
  corrosive, oxidizer/oxidizing agent, neutralizer,
  decomposer

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INTENSIVE PROPERTY

• Definition
• Not dependent upon the amount of matter present.
• Can be used to identify a substance.
• Examples density, ductility, melting point,
  boiling point, color, malleability, crystal shape

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EXTENSIVE PROPERTY

• Changes with the amount of matter present
• Examples size, mass, volume

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CHEMiCAL and PHYSiCAL CHANGES

• Physical change definition
• A change that does NOT alter the substances
  chemical identity.
• Usually, these are easily reversed.
• Chemical change definition
• A change in which a new substance, with new
  chemical properties, is formed.

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PHYSICAL CHANGES

• Dissolving a substance
• State changes
• Solid to liquid melting (fusion)
• Liquid to solid freezing
• Liquid to gas evaporation (vs. boiling)
• Gas to liquid condensation
• Solid to gas sublimation
• Gas to solid deposition

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CHEMICAL CHANGES

• Examples
• Burning
• Rusting
• Decomposition
• Fermentation
• Corrosion
• Digestion
• Photosynthesis

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MSDS

• Check a material safety data sheet for chemical
  and physical properties.
• Circle all properties then label with C or P.
• Are they quantitative or qualitative?
• Are they intensive or extensive?

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DEMONSTRATION

• Before, during, after.
• Are your observations qualitative or
  quantitative?
• Evidence of a chemical reaction?
• Real world applications of the reaction?

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CHEMiCAL REACTiONS

• Written in the form
• Reactants ? Products
• Atoms are rearranged, not created or destroyed.
• Include states in ( )

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4 observations that indicate a chemical reaction

• Gas formation bubbles or odor
• Formation of a precipitate (ppt) an insoluble
  solid that fall out of a mixture of solutions
• Color change
• Energy change
• Endothermic energy is absorbed
• Exothermic energy is released

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SAMPLE CHEMiCAL REACTiONS

• 1. potassium iodide reacts with lead nitrate to
  form a ppt.
• 2. sodium bicarbonate reacts with acetic acid to
  form

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CLASSIFICATION of MATTER
MATTER
MIXTURES

• PURE SUBSTANCES

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PURE SUBSTANCES

• Every sample has the same properties and same
  exact composition
• Cannot be separated by physical means

COMPOUNDS
ELEMENTS
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ELEMENTS

• Made up of 1 type of atom
• Cannot be decomposed by a chemical change
• monatomic 1 atom
• diatomic 2 atoms
• MEMORIZE H2, N2, O2, F2, Cl2, Br2, I2
• triatomic 3 atoms
• Example O3
• Allotropes 2 or more forms of the same element
• Example O2, O3, diamond, graphite
• Examples- Cl2, iron, gold, diamond, sodium, ozone
  (O3)

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COMPOUNDS

• Always have the same composition.
• Can be broken down into elements during a
  chemical change.
• Examples- sugar ( sucrose C12H22O11) H2O,
  ammonia (NH3) sodium
• sodium bicarbonate, potassium permanganate, table
  salt

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MIXTURES

• combination of 2 or more pure substances.
• can be separated by physical means
• have variable composition

HOMOGENEOUS
HETEROGENEOUS
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HOMOGENEOUS

• uniform composition
• called solutions
• Can be (g)/ (l), (s)/ (s), (l)/(l)
• will not settle out
• Examples- acids, bases, vinegar, hot tea, air,
• steel, kool-aid, ink, tap water, 14K gold, brass

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HETEROGENEOUS

• Variable composition throughout
• Differences may be detected with the naked eye
• or a microscope
• Can settle out
• Examples- italian dressing, veggie soup, milk,
  sprite,
• chocolate chip cookies, soil, muddy water, iced
  tea,
• concrete

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PHYSICAL METHODS of SEPARATING MIXTURES

• Used to separate HETEROGENEOUS and HOMOGENEOUS
  mixtures.
• Do NOT alter the materials involved.
• Only depend on PHYSICAL changes.

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CHROMATOGRAPHY

• Separates components of a mixture by comparing
  with attraction for a mobile phase (usually
  alcohol) vs. a stationary phase (usually paper).

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CENTRIFUGE

• Separation done by high speed spinning. Will
  separate the components based on different
  densities.

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DISTILLATION

• Separation of liquid mixtures based on
  differences in boiling points.

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EVAPORATION and FILTRATION

• Evaporation - Separate a solid from an aqueous
  solution by evaporating the water. (May cause
  other aqueous substances to come out of solution
  too).
• Filtration - Separate a solid from an aqueous
  solution using filter paper.

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Magnetism

• Separation of solids based on magnetic
  properties.

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CHEMICAL METHODS of BREAKING DOWN COMPOUNDS

• Used to break compounds down into their component
  elements.
• Chemically alter the compound.
• A chemical reaction must occur.

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DECOMPOSiTiON REACTiON

• Elements formed from the break down of a
  compound.
• Ex. NaCl ? Cl2 2Na
• MgO? O2 2Mg
• Hydrolysis breakdown of water using electric
  current (electrolysis)
• Ex. 2H2O ? 2H2 (g) 2O2(g)

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HOMOGENEOUS MIXTURES

• Recall that solutions are homogeneous mixtures.
• A solution is made up of a SOLUTE dissolved in a
  SOLVENT
• When the solvent is WATER, it is known as an
  aqueous solution and is symbolized using (aq).
• ACIDS and BASES are 2 common types of aqueous
  solutions with distinctive properties made by
  dissolving gases or solids in water.

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ACIDS

• Sour taste
• Conduct electricity (electrolytes)
• React with metals to produce hydrogen gas
• Include a H in their formula
• Can be strong (ex. sulfuric, hydrochloric) or
  weak (acetic)
• Produce H (or H3O) in solution
• Have a pH between 0 and 7
• Can neutralize a base

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BASES

• Taste bitter
• Known as alkaline solutions
• Conduct electricity
• Can be strong (NaOH) or weak (NH3)
• Produce hydroxide ion (OH-) in soltuion
• Have a pH value between 7 and 14
• Can neutralize and acid
• Buffer substances that resist changes in pH