Sec 4 Mid-Year Review

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Sec 4 Mid-Year Review

• Applied Science

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The periodic table
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Review of the Atom
Proton () Neutron (o) Electron (-) Orbit
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How it works

• Each column of the table are called
  groups/families.
• Each member of a group has the same number of
  valence electrons

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Important Definitions

• Valence Electron
• Number of electrons on the last orbit of the
  atom
• A Group corresponds to the columns of the
  periodic table. All elements of a group share
  similar properties such as reactivity (they have
  the same number of valence electrons).

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Group 1A Alkali

• 1st column except hydrogen
• They are soft and highly reactive
• Must be stored in oil due to their high
  reactivity and are never found in their elemental
  state in nature but always as a compound

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Group 2A Alkaline Earth Metals

• Highly malleable and reactive, they burn easily
  in presence of heat
• Never found in their elemental state but can be
  exposed to air (often stored in oil)
• They often form the compound of rocks

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Group 7A Halogens

• Salt creator
• Second to last column
• Non-metals that react easily to form compounds
  including salts

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Group 8A Noble Gases

• Final column
• Very stable
• Can be found in their elemental state

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Important Definitions

• A Period corresponds to the rows of the periodic
  table. All elements of the same period have the
  same number of orbits/shells

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Other divisions

• The staircase indicates the separation of the
  metals (under the stair case) from the non-metals
  (above the stair case).
• The metalloids are located on either side.

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Other divisionsMetals

• Generally good conductors of electricity and heat
• Ductile and malleable
• Usually shiny
• All are solid at room temperature (except Hg)
• Many react with acids

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Other divisionsNon-Metals

• Poor conductors of electricity and heat
• Many are gases at room temperature
• The solid non-metals can easily be reduced to
  powder

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Other DivisionsMetalloids

• Properties depend on conditions
• Seven elements that share properties with the
  metals and non-metals.
• Semi conductors (are good conductors in certain
  conditions, bad in others

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Representing the invisible
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General Rules

• Electrons seek to fill the shells nearest the
  nucleus before occupying a further shell
• The 1st shell contains a maximum of 2 electrons
• The 2nd shell contains a maximum of 8 electrons
• The third shell 18 but after 8 the fourth shell
  fills up first

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Lewis Notation

• Notation in which only the valence electrons
  (electrons on the last shelf) are represented

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Rutherford-Bohr

• Important rules
• the period indicates the number of shells
• the group indicates the number of valence
  electrons
• the atomic number indicates the total number of
  protons and electrons in the atom

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Simplified Atomic Model

• Clearly shows the number of protons and neutrons
  in the nucleus
• The number of neutron equals the relative mass
  (rounded to the nearest whole number) the
  atomic number
• The electron and shells are similar to that of
  Rutherford Bohrs model

p nº
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Chemical Changes
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Chemical Reactions

• a) Definition
• A reaction that alters the nature and
  characteristic properties of matter.
• The atoms are rearranged.
• New molecules are formed

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Chemical Reactions

• b) Observable characteristics
• A chemical reaction occurs when
• A gas is released
• Heat is absorbed (endothermic) or released
  (exothermic)
• Light is emitted
• The color changes
• A precipitate forms

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Chemical Reactions

• c) Types of chemical reactions
• i) Basic reactions
• Synthesis
• Two or more reactants become one product
• Decomposition
• One reactant is decomposed into two or more
  products
• Oxidation
• A reaction where one of the reactants is oxygen
  (O2)
• Precipitation
• A reaction where two liquid reactants form a
  solid product

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Chemical Reactions

• ii) Other chemical reactions
• Acid-Base Neutralization
• Reactants Acid Base
• Products Water Salt
• Combustion
• Type of oxidation that releases a large amount of
  energy
• Combustion requires
• Oxidation agent
• Ignition temperature
• Fuel

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Chemical Reactions

• Cellular respiration
• Takes O2 glucose to form CO2 water energy
• Photosynthesis
• Takes CO2 water energy to form O2 glucose

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Solutions
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Important Definitions

• Molecule
• A group of two or more chemically bonded atoms
• Ion
• - an atom that has become electrically
  charged by loosing or gaining one or more
  electrons
• An ion is negatively charged when it has more
  electrons (-) than protons ()
• An ion is positively charged when it has less
  electrons than protons

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Solutions

• A) Characteristics of solutions
• 1. Solubility
• 2. Concentration
• 3. Electrical Conductivity
• 4. pH

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Properties of solutions

• 2. Concentration
• Definition
• The amount of solute placed in a given solvent
• Once the concentration of a solution reaches the
  solubility point we have a saturated solution
• Can be measured in (g/100ml)
• Can be measured in g/L (g/1000 ml)
• Can be measured in ppm (g/1 000 000 ml)
• Can be measured in mol/L

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Static electricity
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Charging an object

• By friction

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Charging an object

• By friction
• Start with two neutral objects
• When rubbing the two objects together, electrons
  from one object will be ripped off by the atoms
  of the second object
• End two objects with opposite charge

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Charging an object

• Conduction
• One charged object touches a neutral object
• The Charged object shares its charge with the
  neutral object
• We are left with two objects of the same charge

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Charging an object

• Induction
• One neutral, one charged
• Without touching the objects together, the
  charges in the neutral object will separate
• One charged, one partially charged

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Questions complete the following chart
Original charge of objects What occurs? End charge of objects
Friction Two Neutral Rub them together Oppositely charged objects
Conduction One neutral Touch Charges are shared
Induction One neutral Do not touch One charged one partially charged
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Dynamic Electricity
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Electrical functions

• Role that a component plays in the control or
  transformation of electric current
• 1. Power supply
• Provides the energy that makes the current flow
  through the wires and components of a circuit
• Battery
• Electrical outlet
• Photovoltaic cell

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Electrical Functions

• 2. Conduction
• Is the electrical function performed by any
  component that can transmit electric current from
  one part of a circuit to another.
• Printed circuits
• Wires
• 3.Insulation
• Performed by any component that prevents an
  electric current from flowing
• Plastic coating on wires

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Electrical functions

• 4.Protection
• Performed by any component that can automatically
  cut current flow in the event of a power surge.
• Fuses
• Breakers

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Types of circuits

• Series
• Components are connected end to end
• The current can only follow one path
• If one element of the circuit is out, nothing
  works
• The resistance of the elements is added up
• Parallel
• Circuit that contains at least one branch
• If one element is defective the other elements on
  other branches will still functions
• The Total resistance is less than in parallel

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Magnetism
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• Magnetic field of a live wire
• The thumb points in the direction of conventional
  current
• The fingers show the direction of the magnetic
  lines
• Magnetic field of a solenoid
• What is a solenoid
• Cylindrical coil of live wire
• Fingers point in the conventional sense of
  current
• The thumb shows the direction of the magnetic
  field lines inside the solenoid

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• Will the magnetic field be clockwise or counter
  clock wise

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Magnetism quick tricks

• Quick Trick 1
• Magnetic field lines always go from North to
  south
• Quick Trick 2
• In a solenoid
• if the North is to your right, the positive is
  located on the side that goes under the wire
• If the North is to your left, the positive is
  located on the side that goes over the wire