Science 9: Chemistry (Topics A, B, C, D)

Caustic or Corrosive

Property of materials that actively react with another substance, causing it to break down (sometimes referred to as "eaten away")

Explosive

The fundamental concept behind explosives is very simple. An explosive is just something that burns or decomposes very quickly, producing a lot of heat and gas in a short amount of time. Any explosive reaction involves one chemical reacting violently with oxygen.

Evidence of chemical reactions

Change in colour (unpredictable)

Change in odour (unpredictable)

Formation of a solid (precipitate)!

Formation of a gas (effervescence)

Baking soda and vinegar create carbon dioxide gas. Your flatulence is evidence of methane gas effervescence. Don't confuse with state change from liquid to gas.

Exothermic

They release more energy than they take in. The resulting product loses energy but the surrounding environment gains energy.

Endothermic

They take in more energy than they release. The resulting product gains energy but the surrounding environment loses it.

Combustion

methane + oxygen reacts to form carbon dioxide + water

Cellular respiration

food (sugar) + oxygen reacts to form carbon dioxide + water

Corrosion

iron + oxygen reacts to form iron oxide (rust)

Concentration

The greater the concentration of the reactants, the faster the reaction proceeds since there is a better chance of reacting atoms bumping into one another when there are more of them.

Temperature

Adding thermal energy increases reaction rate since atoms are moving faster and there is increased chance of collisions but that is not the only reason. In order for particles to react with one another they must have a certain amount of kinetic energy and the increased temperature provides that energy boost.

Surface area

Increasing the surface area by crushing up the reactants makes the reaction speed up since more reacting particles are exposed at the start of the reaction.

Catalyst

A ___ speeds up a chemical reaction, but is not changed or used up by the reaction.

Electrolysis

When electricity is run through water, it separates the hydrogen and oxygen.

Law of Conservation of Mass or Matter.

This law states that mass (or matter) is not created or destroyed in a chemical reaction.

Reactants

Chemicals that are added together

Products

New chemicals resulting from the reaction

closed system

The mass of reactants and products will be the same in a _ because all matter has been contained and not allowed to escape.

Dmitri Mendeleev

recognized a pattern similar to a solitaire game and ordered the elements in rows and columns. This classification of elements became known as the periodic table.

element

a pure substance with characteristics that make it different from every other element.

Democritus

was a Greek philosopher, and the first person to suggest that matter was made up of tiny, invisible particles that we now know as atoms.

Alchemists

were trying to discover how to make gold but came up with many tools that furthered the study of real

chemistry at a later date.

John Dalton

inferred that atoms must be like billiard balls with charged particles embedded in them.

J.J. Thompson

was the first scientist to come up with the idea of subatomic particles and he created the "raisin bun" atomic model.

Ernest Rutherford

discovered that certain subatomic particles were too massive to pass through a gold screen that would allow electrons through, and inferred that there must be a dense nucleus in atoms.

planetary model

Rutherford's model, with the nucleus in the middle and electrons orbiting around it, became known as the ------------ of the atom.

James Chadwich

focused his work on the nucleus and discovered that there were two different kinds of particles there - protons and neutrons.

Niels Bohr

discovered an atomic model with electrons in energy levels (orbital shells) around the nucleus.

Bohr model

The model still used by chemists was discovered by Bohr, and is called the ---------. It introduced the idea of energy levels in atoms.

quantum model

The most recent atomic model is called the quantum model and has given rise to the science of quantum physics.

Atom

The ----- is the smallest part of an element that still has all of the properties of that element.

subatomic particles

Atoms are made of even smaller parts called -------- ----------. These include protons, neutrons and electrons.

nucleus

The ------- of an atom is at the centre and contains both protons and neutrons. The nucleus makes up the mass of the atom.

Protons

are positively charged subatomic particles in the nucleus of an atom.

Neutrons

and neutral (no charge) subatomic particles in the nucleus of an atom.

Electrons

are negatively charged subatomic particles that orbit around the nucleus of an atom.

density

The mass of an atom determines the ------- of an element made from that atom. Materials with greater atomic mass form substances that are more dense.

atomic number

The -------- ---------- tells how many protons are in the nucleus.

atomic mass

The total mass of all protons and neutrons in the nucleus is the -------- (measured in amus or atomic mass units).

element symbol

Each box on the Periodic Table represents one unique element. The ---------- -------- is the letter that represents that element for chemists.

ionic charge

An atom that has one too many electrons is called a negative ion because it has an overall negative ------- ------. A positive ion has too few electrons.

ion

is an atom with an unbalanced electrical charge - either too few or too

many electrons to balance the positive protons in the nucleus.

isotopes

The number of protons in in an atom of an element never change. The number of neutrons can, and -------- are atoms with of a specific element with different numbers of neurons.

periods

Horizontal rows on the periodic table represent the number of shells for electrons on an atom. All atoms in these ------- have the same number of shells and rings.

groups or families

Vertical columns are called ----- ----- ----- and all elements in a column have the same number of electrons in their outer shell. Because of this, their chemical behavior is very similar.

Valence electrons

are on the outermost ring and control how reactive a particular element will be.

Ionic compounds

are the result of a chemical reaction between a metal and a non-metal.

Ionic bonds

are the result of opposite electrical charges attracting. The metals lose and electron and the non-metals gain one.

Molecular compounds

are the result of a chemical reaction between two non- metals.

covalent bond

Molecular compounds are held by a ------- ------ in which valence electrons are shared between atoms of two. Non-metals.

WHMIS

The Workplace Hazardous Materials Information System

oxidizing materials

Substances that supply oxygen that can be used as a fuel for fire

Compressed gas

kept in a metal canister and is under very high pressure. If the canister is heated, the gas can expand, causing the canister to explode

biohazards

Dangerous materials that are living or was living

waft

using your hand to carefully fan fumes toward your face.

hazard symbols

specify they type of hazard, and the level of danger.

physical properties

Properties that can be reversed and do not result in a new type of material

chemical properties

Properties that are observed only when one substance irreversibly interacts with another, creating a new substance

combustion

A chemical reaction that involves flames and burning

corrosion

A chemical reaction that involves rusting or eating away of material

A state of matter

whether it is a solid, liquid, gas or plasma

plasma

If you add enough heat to a gas, the atoms will reach an even higher energy state

freezing point

The temperature at which liquid change to solid

boiling point

The temperature at which liquid change to gas

melting point

The temperature at which solid changes to liquid

ductile

Metals can be stretched into long, thin wire

malleable

Metals can be rolled into thin sheets such as aluminum foil

Solubility

a physical property that refers to how much of a substance can be dissolved at a given temperature

Density

a substance's mass compared to its volume and is a physical property

conductivity

The property of how well they conduct energy, usually heat and electricity

matter

Anything that takes up space and has mass

Atoms

the smallest particles of matter that have specific, identifiable properties.

Molecules

consist of two or more atoms

classification of matter key

a tool to differentiate matter based on the configurations and type of atoms.

Pure substances

contain all of the same kind of material (elements or molecules)

compound

A pure substance consisting of all the same kind of molecule

mixture

Matter containing different types of molecules

solution

When there are more than two types of molecules but it looks like a single substance

mechanical mixture

When there are more than two types of molecules and you can clearly distinguish each one

Metals

materials that are malleable, ductile, and good conductors of heat and electricity

Metalloids

materials that have properties in between metals and non-metals. They are semi-conductors.

Non-metals

materials that are good insulators and are often brittle.

IUPAC

The rules for naming chemical compounds are the responsibility of an organization of chemists

chemical formula

like a recipe for creating a molecule since it tells what elements to put in and how many of them.

chemical equation

shows what happens in a chemical reaction - what combines at the start and what is created in the end.

reactants

combined at the start of a chemical reaction.

products

formed at the end of a chemical reaction.

replacement reaction

A common reaction type in which elements simply switch partners between

reactants and products