Download Study Sheet for Chemistry and Physics Chemistry Atomic Structure

Study Sheet for Chemistry and Physics
Chemistry
Atomic Structure – Protons (positive) and neutrons (neutral) and clustered in the VERY dense center of
the atom. Electrons (negative) spin in electron clouds around the nucleus. The negative electrons are
electromagnetically attracted to the positive nucleus. Neutrons are the heaviest particle, the protons,
and lastly electrons. To find the number of protons and electrons – find the atomic number. The number
of neutrons can be found by taking the difference between the atomic number and the atomic mass
(rounded to nearest whole number). The atomic mass (measured in amu – atomic mass unit) can be
found by adding protons and neutrons together.
Matter
Atom – smallest unit of an element – can’t be broken down any further
Element – cannot be broken down by any chemical means
Molecule – combination of 2 or more ATOMS – Example O2 or H2O
Compound - combination of 2 or more ELEMENTS (they are chemically combined) – Example H2O or CO2
**All compounds are molecules, but not all molecules are compounds**
Mixture – combination of substances that are NOT chemically combined – Example: a tossed salad
Suspension – mixture where the particles settle out – Example: Italian salad dressing
Solution – mixture where a solute is dissolved into a solvent, but can be separated. Example: salt water
Solute – the particle that is dissolved in a solvent. Example: salt
Solvent – the particles into which a solute is dissolved. Example: The UNIVERSAL SOLVENT – WATER!
Colloid – mixture where solid particles separate. Example: Jello or Milk
Periodic Table – Vertical columns are called Groups or Families. All of these elements share similar
properties and all have the same number of valence electrons (the outermost electrons). Horizontal
rows are called Periods. Periods tell you how reactive the element can be or how well an element
conducts electricity. The bottom group is called the Lanthanides and Actinides. They are removed for
space reasons only. Most ALL of your METALS are to the left of the staircase (except Hydrogen). ALL of
you nonmetals are to the right of the staircase. The metalloids are located along the staircase and they
have properties of metals and nonmetals. Valence Electrons can be found relatively easy by looking at
the Group number. Starting from the far left – that is Group 1 – Group 1 has 1 Valence electron, Group 2
has 2 valence electrons. Groups 3 -12 vary. Groups 13-18 can be found by subtracting 10 from the group
number. The magic number is 2 (for the lower number elements) or 8 for the higher elements. The
closer to 8 (or 2) the more stable the atom will be.
Bonding: 3 types
Ionic – the gaining or losing of ELECTRONS. Results is a positive or negatively charged atom. If electrons
are LOST, the atom is POSITIVE. If electrons are GAINED, the atom is negative. Normally occurs between
a metal and a nonmetal.
Covalent – the sharing of electrons. Usually a nonmetal and another nonmetal.
Metallic – bonding between 2 or more metals. Can be ionic or covalent.
Counting Atoms
H2O – has 3 atoms (2 H and 1 O)
2H2O – has 6 atoms (4 H and 2 O) – you simply distribute the Coefficient throughout the compound.
Balancing Equations
Here is a website for you to practice with!
http://richardbowles.tripod.com/chemistry/balance.htm#part1
Laws
Law of Conservation of Matter/Mass – in a chemical equation, whatever you started with you must also
end with. The law states that matter/mass cannot be created or destroyed.
Law of Conservation of Energy – during chemical reactions energy cannot be created or destroyed, so
whatever you started with you must also end with.
Heat Transfer: 3 types
Radiation: transfer in waves – heat you can feel
Conduction: transfer by direct contact – touching a hot pot
Convection: heat transfer through a fluid (liquid or gas) in a circular pattern – like water boiling in a pot
Acids/Bases
Acids – sour to taste – pH of 0-6 examples: vinegar, citrus fruits, tomatoes
Bases – bitter to taste – typically slippery to feel – pH of 8-14 – examples: bleach, soap, antacids
When you combine an acid and a base, they typically form a salt.
Charles Law vs. Boyles Law
Charles – at a constant pressure…volume increases and temperature decreases – the opposite is true as
well.
Boyles – at a constant temperature (think BOILING – sounds like BOYLES!) – volume and temperature
increase and decrease at the same rate
Physics
Speed – distance traveled over time (see Formulas and Units section on how to calculate) – example
65km/h
Velocity – speed in a SPECIFIC direction – Example 65km/h NW
Acceleration – rate at which velocity changes, so any change in speed or direction is considered
acceleration. Positive acceleration (faster) and Negative Acceleration/Deceleration (slower).
Continuous Acceleration: acceleration in a circle. Constantly changing direction, so constantly
acceleration.
Force – any push or pull – measured in newtons
Net Force – combination of all forces (see formulas for calculation)
Balanced force – object at 0 Newtons - typically stationary
Unbalanced force – object in motion. This is what causes a balanced force to move!
Laws
Universal Law of Gravitation – 2 parts:
1. Gravitational force increases as MASS increases
2. Gravitational force increases as DISTANCE decreases
Newton’s 1st Law – Object in motion stays in motion, object at rest stays at rest unless it is acted upon
by an unbalanced force. Bumper cars are an excellent example.
Inertia – an objects resistance to a change in motion
Newton’s 2nd Law – acceleration depends on mass and the force applied. Compare pushing an empty
grocery cart to pushing a full grocery cart. As MASS increases, the FORCE required to move the mass
increases!
Newton’s 3rd Law – For every action, there is an equal and opposite reaction. Difficult to see, imagine
kicking off of a wall while swimming.
Gravity and Motion
All objects fall at the same rate due to the force of gravity.
ALL objects accelerate toward Earth at a rate of 9.8 m/s2! So for every second that an object falls, simply
multiply the time (in seconds) by 9.8 to compute the Velocity of a Falling Object! (see formulas)
Terminal Velocity – Speed of a falling object increases, so does air resistance. So air resistance pushes up
while the object falls. When these 2 factors balance out – terminal velocity is reached. The object falling
is now BALANCED!
Free fall –ONLY possible in a vacuum! No forces can act on the object as it falls.
Projectile Motion – an object that is thrown will accelerate horizontally and then vertically as gravity
takes over
Work – is done when force causes an object to move. The force and the movement MUST be in the
same direction for it to be considered work. (See formulas)
Power – the rate at which energy is transferred (see formulas)
Simple Machines – 6 types
Lever – a bar that pivots around a fixed point (fulcrum)
1st class lever – fulcrum is in the middle…example: a see saw, or the rowing mechanism on a row
boat.
2nd class lever – fulcrum and load (weight) are on the same end…example: wheelbarrow or oldfashioned bottle cap opener
3rd class lever - fulcrum on opposite end from load…example: your elbow or swinging a hammer
Pulley – consists of wheels and a rope or cables. Three kinds:
Movable: can be pulled from either direction…example: raising a flag on a pole
Fixed: pulled from one side…example: pulling a water bucket from a well
Block and Tackle: has multiple wheels to assist with lifting heavy objects
Wheel and axle - a wheel that pivots on top of a cylinder…example: doorknob, or steering wheel
Incline Plane: a straight, slanted surface…example: a wheelchair ramp
Wedge – a pair of inclined planes that can move…example: a door stopping wedge or a knife
Screw – an incline plane wrapped around a cylinder…example: the lid to a jar or a wood screw
Formulas and Units
Area: L X W, measured in cm2
Volume of a regular solid: L X W X H, measured in cm3
Density = Mass / Volume, measured in g/ml or g/cm3 (depends what kind of object)
Number of Protons or Electrons: Equal to the Atomic Number of the element
Number of Neutrons: the difference between the atomic number and the atomic mass rounded to the
nearest whole number
Atomic Mass: add your protons and neutrons together, measured in amu’s (atomic mass units)
Speed: distance / time, measured in m/s
Average Speed: total distance/ total time, measured in m/s
Resultant Velocity: if the objects are traveling in the same direction - add them; if they are traveling in
opposite directions – take the difference. Keep the direction of the highest number, measured in m/s
Average Acceleration: final velocity-starting velocity/time it takes to change velocity, measured in m/s2
Net force: add forces together that are moving in the same direction. Take the difference between
forces that are moving opposite to one another, measured in Newtons
Velocity of a falling object: change in V = g X t (g = gravity and gravity is ALWAYS 9.8m/s), measured in
m/s
Acceleration = force/mass (Newton’s 2nd Law), measured in m/s2
Force: mass X acceleration, measured in newtons
Work: force X distance, measured in joules (sometimes called newton-meters)
Power: work / time, measured in watts
Wave speed: wavelength X frequency, measured in m/s (Frequency is measured in Hertz – Hz)