Chemistry

matter

anything that has mass and takes up space by having volume

five states (only be assessed on 3) — four are natural, one is not

• solid

• liquid

• gas

• plasma

• bose-einstein condensates

solid: shape, volume, compressibility

fixed, fixed, low

liquid: shape, volume, compressibility

shape of container, fixed, moderate

gas: shape, volume, compressibility

shape of container, volume of container, high

changing states of matter

can be changed by adding/removing energy

once state has changed, not a new substance

pure substances

composed of a single type of particle. same properties throughout

types of pure substances

element: pure substances that cannot be broken down further by chemical reactions (ex. hydrogen, gold magnesium)

compound: made up of two or more elements (ex. water, CO2)

mixtures

substances that contain two different kinds of particles mixed (not combined) together

types of mixtures

• homogeneous (solutions): uniform throughout (eg. fruit punch, sugar water, saline solution)

• heterogeneous (mechanical mixture): composition is not uniform (you can see the different parts (eg. pizza, salad, burger)

solutions

formed with solute and solvent

solute: being dissolved

solvent: does the dissolving

mechanical mixtures (types)

suspension: particles will seperate out from the mixture (oil and water, muddy water)

colloid: particles will not settle, even with intense spinning in a centrifuge

the clue that a mixture is a colloid and not a solution is

it scatters light when a laser is pointed through it. you can see the beam travel through the mixture.

particle theory of matter states that:

1. all matter is made up of small particles

2. each substance has its own unique particle, that is different than the particles of other substances

3. all particles have space between them

4. particles are always moving. adding more heat (energy) causes particles to move more

5. all particles are attracted to each other

kinetic energy: solid

very low

kinetic energy: liquid

low

kinetic energy: gas

very high

particle motion: solid

vibrate and rotate in fixed position

particle motion: liquid

slide over each other

particle motion: gas

move at high speeds

which state are the particles moving the fastest?

gas

which state are particles moving the slowest?

solid

which state are the attractive forces between the particles the greatest?

solid

which state are the attractive forces between the particles the weakest?

gas

why does ice melt when heat is added?

as heat energy is applied to the ice, the particles move faster until the attractive forces between the particles weaken enough that they slide around each other and form a liquid.

why does water evaporate when heat is added?

as heat energy is applied to the water, the particles move faster until the attractive forces between the particles weaken enough that they move far enough apart to form a gas.

why is the shape of a solid fixed?

because the particles are closer together in a fixed position with strong attractive forces holding them in place. they vibrate and move around less than the particles of a liquid or gas.

why is a solid difficult to compress?

the particles of a solid are difficult to compress because they are already so close together and in a fixed position.

what is the difference between water at 20^oC and 50^oC?

water at 20 degrees has slower moving particles and slightly stronger attractive forces compare to the water at 50 degrees.

Every substance can occur in any of the three states of matter.  For example, oxygen can exist as a gas at room temperature, a liquid at –118^oC, and a solid at   –220^oC.  Describe how the motion of the particles would change as the temperature was increased from –230^oC to room temperature.

The particles of oxygen would barely move at –230^oC, as energy is added and the temperature approaches –118^oC, the particles move faster and faster until they become a liquid.  This continues with the particles gaining speed all the way to to room temperature where oxygen is a gas.

physical property

characteristic of matter that can be observed and measured without changing its chemical identity.

qualitative physical property

characteristic that can be observed (using senses) and described using words.

quantitative physical property

characteristic that can be measured and described using numbers and units.

qualitative physical properties examples

• state of matter

• colour

• optical clarity (transparent, translucent, opaque)

• lustre (shiny — high lustre, dull — low lustre)

• hardness (how easy to scratch, resistance to pressure)

• brittleness (how easy to break)

• form (crystalline — regular shaped; amorphous — irregularly shaped)

• texture

• malleability (flatten a material)

• ductility (ability to make it into a wire — most metals)

• viscosity

• odour

• taste

• conductivity (solids and liquids to transfer heat/electricity)

quantitative physical properties examples

• melting point

• boiling point

• density

• solubility

chemical property

characteristic of matter that is observed during a reaction in which the chemical composition or identity of the substance is changed.

chemical properties examples

• flammability (ability to burn/ignite)

• toxicity (substance can damage an organism)

• combustibility (how easy a substance bursts into flame)

• reactivity with other chemicals (tendency to undergo a chemical reaction)

• heat of combustion (amount of heat released)

what is density?

a physical property that relates to how much matter (mass or grams) that can fit in a desired volume (cm³ or mL)

density formula

density = mass / volume

mass

amount of material in an object. measures with a balance, usually in grams

volume

amount of space an object occupies. measured using a graduated cylinder or is determined by calculation using the dimensions of the object. volume is measured in cm³ or mL.

finding volume (prism)

lwh

volume (cylinder)

v = πr²h

volume of a liquid

measure the volume of a liquid with a graduated cylinder

volume of an irregularly shaped object

subtract initial amount and new amount

guess method for calculations

g- given

u- unknown

e- equation

s- substitute and solve

s- statement

physical changes

alters the form of a substance, but does not alter the composition of the substance

chemical changes

an alternation of a substance’s composition. a new substance is always formed.

examples of physical changes

melting, shredding, boiling, chopping

examples of chemical changes

combustion, rusting, rotting, digestion

signs of a chemical change

1. new colour or odour appears

2. heat or light is given off

3. bubbles of gas formed

4. a precipitate (solid formed from two solutions) is formed

5. change is irreversible or difficult to reverse

chemical reactions

process in which one or more substances, also called reactants, are converted to one or more different substances, known as products

reactants

substance that takes part in and undergoes change

products

substance at the end of a chemical reaction

word equations

seperated with + signs and the product is written after an —>

Elements

basic building blocks of matter, simplest pure substance made of only one type of atom

Physical Properties of Metals

solid, hard, malleable, ductile, shiny, high conductivity, opaque

Where are metals on the Periodic Table?

metals are on teh left side of the staircase

Where are metalloids

On the staircase, are solid, brittle and share common properties with metals and nonmetals

Where are the nonmetals

located right side of staircase can be gas, liquid or solid, nonlustrous, lower melting points

Where are the Lanthanides and Actinides

located under main table

Atomic Mass

amu

periods

horizontal rows

families and groups

vertical columns

Alkali

group 1 - soft solid metals, shiny silver in color, extremely reactive, reacts with water to produce hydrogen gas.

Alkaline Earth Metals

solid metals, more dense than group 1 - group 2

Halogens

nonmetals, solid liquid gas, extremely corrosive and reactive - group 17

Noble / Inert Gases

group 18 - nonmetals, odourless, colorless, very stable, unreactive, rarely combines with other elements

Billiard Ball Model - JOHN DALTON

proposed atoms were small indivisible balls, proven wrong

Gas Discharge Tube - HEINRICH GEISSLER

• improved hollow gas tubes with electrolodes, and when gas was removed, it glowed green.

J.J Thompson: The Plum Pudding Model

concluded tiny particle was passing through tube caused tube to glow green, and that the particles must be repelled from negative side, giving them the name electrons, electrons are negative but atoms are neutral, have very little mass, there must be something else that is positive with lots of matter.

Gold Foil Experiment - Ernest Rutherford

long experiment - included Radium, Lead Block etc.
concluded that there was a dense core in particles call the nucleus, positively charged particles are called protons,

Discovery of Neutron - James Chadwick

concluded that an uncharged particle is called neutron, after observing a hydrogen atom.

Bohr-Rutherford Atom Model

proposed that electrons can only cirlce the nucleus at specific distances like energy levels. Proposed atoms are like solar system.

Ion

atom with one less or more electron.

Cation

an atom that lost an electron to have a full valence electron, metals lose electrons to form positive ions

anion

atom that gained electrons so its valence shell is full, nonmetals gain electrons to be negative ions

stable element

full valence shell

unstable element

not have a full valence shell

naming ionic compounds

metal goes first, then nonmetal goes second. the suffix -ide is added to the end e.g sodium chloride

Subscripts

small numbers just below element symbol in chemical formulae, number of electrons added or lost.