Science Quiz - Review

Lesson #1 - Particle Theory & Phase Changes

The Particle Theory

• Particles are like pixels in our world. Even though we can’t see them, they are what makes up everything around us. The particle theory of matter describes what we know about how these particles act.

• The Particle Theory of Matter

  • All matter is made up of tiny particles.

  • All particles are in constant motion.

  • Temperature affects the speed at which particles move.

• Particle Theory and State

  • Three phases of matter: Solid, Liquid & Gas.

  • In a gas, there are large spaces between particles.

  • In liquids and solids, the particles are close together and have strong forces of attraction between them.

• Phase Changes

  Kinetic Energy: The energy of an object because of motion.

• Recall - the particle theory of matter states that particles are ALWAYS in constant motion.

  Temperature: measures the average kinetic energy of the particles of an object.

  • Like a speedometer for how fast particles are moving!

  • DOES NOT measure how hot or cold something feels - this is qualitative.

  • Higher Temperature = faster moving particles = takes up more space = higher reading on the thermometer.

  Temperature Scales

• Absolute Zero: The temperature at which the motion of particles theoretically STOPS. Never been accomplished in real life.

  • Absolute Zero is the 0 on the Kelvin Scale.

    Heat and Thermal Energy

  • Heat: The flow of energy from warmer places to cooler places due to a difference in temperature.

  • Thermal Energy: The overall energy of a system that is responsible for the temperature (speed of the particles)

    Phase Changes: When a substance changes from one state of matter to another.

    
    

  • Lesson #2 - Classifying Matter

    All Matters are made of particles. Matter is anything that has a mass and takes up space.

    Classifications of Matter

    • Matter can be classified as either a pure substance or a mixture.

      Pure substance: Made of the same material throughout and have the same physical and chemical properties throughout.

      Classifications of Pure Substances

    • Pure substances can be classified as either elements or compounds.

Element: The simplest form of matter, which cannot be broken down.

• Any amount of a pure element retains the unique physical and chemical properties of that element.

• There are 118 known elements, organized in the Periodic table.

• Note: Chemical Symbols are used to represent elements.

  • 1 or 2 letters are used, but only the first letter is capitalized.

Compounds: Pure substances that are made of two or more elements chemically bonded together.

Chemical Formulas: Represent how many of each element are part of the compound.

• ex. H₂O = two hydrogen and one oxygen.

  Properties of Compounds

• A compound has different properties than the individual elements in it

• Energy must be taken in or given off when a compound is broken apart or put together

• Separating the elements in a compound requires a chemical reaction.

  Mixtures: Matter that is made up of more than one substance that are not chemically bonded together. (their parts are physically combined (aka mixed)).

  • Mixtures are NOT pure substance

  • Parts of a mixture keep their own properties because a new substance has not been formed.

    Classifying Mixtures: Mixtures can be classified into homogeneous and heterogeneous.

    Homogeneous Mixtures

  • A mixture where the parts are evenly mixed, and they stay evenly mixed, cannot see the different parts - looks the same throughout.

  • Also known as solutions.

    Heterogeneous Mixtures

  • A mixture where the parts are not evenly mixed, can see the different parts - looks the different throughout.

  • Can include suspensions and colloids.

    Suspensions and Colloids

    • Suspensions: a mixture where particles settle and form layers over time.

      Ex. Salad Dressing

    • Colloids: a mixture where particles can be seen in a beam of light

      Ex. Milk

      Lesson #3 - Physical and Chemical Properties of Matter

      Physical Properties

    • A characteristic of a substance that can be determined without changing the composition of that substance.

      Qualitative and Quantitative Properties: Physical Properties can be qualitative or quantitive

    • Quantitative: A property that is measured and has a numerical value.

    • Qualitative: A property that is observed and does not a numerical value.

      Chemical Properties

    • A characteristic of a substance that is determined when the composition of the substance is changed.

    • One of more new substances are produced

  
  

Chemical Properties

• SoCombustibility: to burn

• Toxicity: How poisonous the substance is

• Acidity: How acidic or basic the substance is

• Reactivity: How to substance reacts with another

Lesson #4 - Characteristic Physical Properties

Characteristic Physical Property

• A physical property that is unique to a substances and can be used to identify that substance.

  • Ex: Freezing/ melting/ boiling points & Density.

    Freezing, Melting, and Boiling Points

    Different substances freeze, melt and boi at different temperatures

  • Depends on the particular composition and structure of the substance.

  • Can be used to identify unknown substances

  Applications of Melting Point

  Incandescent light bulbs

  • Use filaments with high melting points so it does not burn out too fast

  Thermostats & Thermometer

• Use alcohols or mercury because they have a very low melting point (liquid at room temperature).

  Fuses

  • Melt at specific heats so the circuit does not overload

    Salt & Ice

  • Adding dissolved impurities (aka salt) lowers the freezing point of water

  • SO water will remain a liquid until -16 degrees C if mixed with salt.

  The Unusual Behaviour of Water

  • Freezes at 0°C and boils at 100°C

    Unusual qualities of water

  • Solid form less dense than liquid form

  • Loses and gains heat slowly

  • Particles highly attracted to one another.

  Adhesion, Cohesion, and Surface Tension

  • Adhesion: Water molecules attracted to other surfaces

    • Ex. Meniscus in graduated cylinder

  • Cohesion: Water molecules attracted to each other

    • Ex. Formation of water droplets

  • Surface Tension: Cohesion at the surface

    • Ex. Insects “walking on water”.

    Density: A density property or physical matter

    • mass per unit volume of a substance

      → Measured in g/cm³ or g/L

    • Density = mass/volume

    • Mass = density x volume

    • Volume = mass/density

    Volume: Amount of space occupied by a substance (can be in solid, liquid, or gas form)

    There are two types of volumes we will see:

  • Solid: How do I find the volume of block? (V = l x w x h) → Measured in cm³

  • Liquid: How do I find the volume of milk in the carton? → Measured mL

    Mass: Measure of amount of matter in a substance (how many atoms it is made of)

  • Mass is an intrinsic property of a substance → Is the same wherever it goes

  • Weight depends on where object is located (Earth vs. Moon)

    Does density change?

  • Density of a pure substance is about the same (constant) for any given temperature

  • As substances heat and cool, they expand or contract, so their density changes slightly

    • Unless otherwise noted, assume that items are measured at 21 degrees Celsius (standard temperature)

    • Density = mass(g)/volume (cm³) weight = mass

      Physical Changes

    • Physical Change: a change that occurs without altering the composition of the substance

      • No new substance is made

      • Often easily reversible

    Chemical Changes

  • A change in the starting substance(s) and the production of one or more new substances

    • A CHEMICAL REACTION!

    Evidence of a Chemical Reaction

  • Colour Change

  • Heat or light produced or absorbed

  • Odour change (good or bad)

  • Precipitate - new solides produced from liquids

  • Effervescence - bubbles of gas produces

  • Difficult to reverse

  Lesson #6 - Patterns on the Periodic Table

The Periodic Table

• Developed in 1869 by Dmitri Mendeleev

  • Only 63 elements at the time

• Organized the elements in order of increasing mass

• Put elements with similar properties in the same columns

• Empty spaces indicated missing elements.

Groups in the Periodic Table

• The periodic table tends to group similar elements together (e.g, metals are ALL together).

Periods and Groups

• Periods: The horizontal rows on the periodic table

• Groups: The vertical columns on the periodic table

  • Also called families

  Metals

• Located left and central on the periodic table

• Solid at room temperature

• High lustre (shiny)

• Generally malleable and ductile

Non-Metals

• Often gas or dull powdery solids

• Low lustre (dull)

• Poor malleability and ductility

  Metalloids - An element that has properties of both metals and non-metals.

Chemical Families - A column of elements with similar properties

Alkali Metals

• Found in group 1

• Shiny, silvery and soft

• Highly reactive

Alkaline Earth Metals

• Found in group 2

• Shiny and silvery

• Not as soft or reactive as alkaline metals

Transition Metals

• Found in the middle of the periodic table

Halogens

• Found in group 17

• Very reactive

• Rarely found in elemental room

Noble Gases

• Found in group 18

• Very unreactive

• Colourless, tasteless and odourless

Lesson #7 - Atomic Theory

Early Atomic Theories

Democritus (400 BC)

• Proposed the existence of atoms based on reasoning but had no evidence

John Dalton (1766 - 1844 , Bowling ball)

• Proposed the first modern atomic theory: elements consist of atoms, which cannot be created, destroyed or divided

Discovering the Electron - J.J. Thompson (1856 - 1940)

• J.J. Thomson (1856-1940): Cathode ray experiment → discovered negatively charged electrons ("plum pudding" model).

Discovering the Electron - Robert Millikan (1909)

• Used charged oli drops falling between charged plates to determin the charge and mass of an electron. (m = 9.11 × 10⁻³¹ kg)

Ernest Rutherford (1911) - “cherry with a pit (early 1900’s)

• Fired positively charged alpha particles at a thing sheet of gold foil and observed some were deflected at weird angles.

  Chadwick - Discovered neutrons (added the third part of neutrons)

• Determined the mass of an atom’s nucleus is greater than the mass of protons alone, so reasoned there must be a neutral particle also (neutrons).

Atomic Spectra

Spectroscopy - the study of spectra in order to determine properties of the source of the spectra.

Emission spectrum - the spectrum of electromagnetic radiation emitted by an atom when it returns to a lower energy state from a higher energy state.

The Bohr Model of the Atom

• Used for the emission spectrum of the hydrogen atom to develop a quantum model for the hydrogen atom

• When an electron gains more energy, it can move into a farther orbit - this is called a transition.

• Ground State - the lowest energy state for an atom.

Successes and Failures of the Bohr Model

Successes - The Bohr model assumes each energy level holds a maximum number of electrons, with lower levels filling first.

Failures - The method works well for the first 20 elements but fails beyond that.

Lesson #9 - How to count atoms

• Isotopes - An atom with the same number of protons but a different number of neutrons

• Ions - atoms that have a positive or a negative charge due to the gain or loss of electrons

• Atomic Mass - the mass of an atom in atomic mass units (amu)

• Mass Number - the number of protons and neutrons in an atoms nucleus

Counting Atoms

• Elements come together in certain combinations to form compounds

  • Chemical Formula: notation that indicated the type and number of atoms in a compound

The Rules & Subscripts

An Elements Written on its own

• Means that there is just 1 atom

• Ex: Na → 1 sodium atom

  • A small number (subscript) after the element

  • represents the number of atoms for the element before it.

• Ex: H₂O - 2 atoms of hydrogen. 1 atom of oxygen.

Brackets

• When you have a compound within a bracket with a subscript, the subscript applies to all elements indie the brackets.

• You need to multiply the outside of the brackets by any subscript number for elements

  • Ex: (NO₃)₂ - 2 atoms of nitrogen, 6 atoms of oxygen.

  Why do Ions Form?

• Atoms are most stable when their valence shell is full

  Metals vs Non-Metals

• Metals tend to form cations because they want to lose electrons

• Non-Metals ten to form anions because they want to gain electrons

  • When an atom loses an electron, it becomes a positive ion.

  • When an atom gains an electron it, becomes a negative ion.

  Ionic Bond

• Ionic Bond: When one atoms gives up one or more electrons to another atom

• Involves the creation of 2 or more ions

• These bonds are very strong due to electrostatic attraction

• Occurs between a metal and a non-metal

  
  

• Lesson #11 - Covalent Bonding

  Covalent Bonding

  Covalent Bond: When one atom shares one or more electrons with another atom

• Occurs between two non-metals

• Covalent compounds are called molecules

  Bonding and Lone Pairs

• Bonding pairs: the shared electrons between atoms of a molecule

• Lone Paris: pairs of electrons not being shated between atoms

  
  

  Ionic vs Covalent