grade 9 chemistry

Atom

the basic (and smallest) unit of a chemical element. Made up of three parts, proton, electron, neutron.

Atomic radius

the average sitance from the centre of an atom's nucleus to its electrons in the farthest orbital.

Boiling Point

the temperature at which a liquid boils and turns to vapor (100°C). The boiling point for fresh water is 100°C.

Binary Compound

2 ionic compounds.

Chemical Change

change chemical properties or composition, resulting in the formation of at least one new substance. The formation of rust on iron is a chemical change.

Chemical Property

a property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed. Combustibility is an important chemical property to consider when choosing building materials.

Combustibility

capable of catching fire and burning; inflammable; flammable. Gasoline vapor is highly combustible.

Compound

a pure substance composed of two or more elements that form a new substance with unique chemical and physical properties. Salt is a compound.

Conductivity

the property or power of conducting heat, electricity, or sound. Electrical conductivity is a necessary property for wiring in our electrical world.

Covalent bond

bond created when two elements share electrons.

Density

the mass of stuff that is packed into a certain space of stuff. Density is mass per unit volume.

Ductility

capable of being hammered out thin, as certain metals; malleable. Copper has high ductility.

Electron

Has a mass of 1/2000 of a proton. Is negatively charged, and located around the atoms in the valence shell and energy levels. Number of electrons = number of protons.

Electronegativity

the ability of the atom to hold onto electrons. Increases from left to right, bottom to top on periodic table.

Element

one of a class of substances that cannot be separated into simpler substances by chemical means. An example of an element can be found in the Periodic Table of Elements.

Evaporation

the process by which any substance is converted from a liquid state into, and carried off in, vapour. Water can evaporate into mist.

Ground

an object that can supply OR remove a large amount of electrons.

Hardness

the state or quality of being hard. The hardness of ice.

Heterogeneous

mixture of two or more substances that are visible.

Homogeneous

mixture of two or more substances that aren't visible.

Isotope

2 or more forms of an element that have the same number of protons but a different number of neutrons. Each isotope has a unique mass number.

Ion

a charged atom that has either gained or lost an electron to become fulfilled. Sodium ion.

Ionic bond

a chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion.

Ionic Compound

a compound made of oppositely charged ions. Formed between metal and non-metal elements. Are a pair of cation and anion. Has a high melting point, repels each other because +/- atoms are aligned, and has electrical conductivity. HCl, NaCl, MgO.

Isotope

2 or more forms of an element that have the same number of protons but a different number of neutrons. Has unique mass number.

Malleability

the state of being malleable, or capable of being shaped, as by hammering or pressing. Gold has a high malleability.

Matter

the substance or substances of which any physical object consists or is composed; something that occupies space. Solid, liquid and gas are the three main types of matter.

Melting Point

the temperature at which a solid substance melts or fuses. The melting point of freshwater is 0°C.

Mechanical Mixture

A heterogeneous mixture; the substances are visible.

Mixture

an aggregate of more than one element/compound. Each retain their own physical or chemical properties. Mixtures can be either homogeneous or heterogeneous.

Molecule

smallest unit of two or more atoms. It can be a compound or an element. DNA is a complex molecule.

Molecular Compound

a compound that contains two non-metal elements. Also called covalent compounds. Are soft, easily crushed, bonds within molecules are strong, but bonds between molecules have weaker forces of attention, have low melting points, doesn't conduct electricity. Co2, O2, Cl2.

Neutron

A particle with no charge, located in the nucleus and has the same mass as a proton. Number of neutrons + number of protons = atomic mass.

Particle Theory

1. Matter is made up of tiny particles (Atoms & Molecules)

2. Particles of Matter are in constant motion

3. Particles of Matter are held together by very strong electric forces.

4. There are empty spaces between the particles of matter that are very large compared to the particles themselves.

5. Each substance has unique particles that are different from the particles of other substances.

6. Temperature affects the speed of the particles. The higher the temperature, the faster the speed of the particles.

Physical Change

a usually reversible change in the physical properties of a substance, as size or shape. Freezing a liquid is a physical change.

Physical Property

any property used to characterize matter and energy and their interactions. Physical properties of an element are any you can feel, touch, see, smell, and taste.

Polymers

a compound composed of repeating sub-units linked together by covalent bonds.

Proton

Has a large mass (same as nucleus), positively charged, and located in nucleus. Number of protons = atomic number.

Pure Substance

a substance that is not mixed with another. Has same composition, parts CANNOT be separated by physical methods. Changes happen at fixed temperatures. Can be elements or compounds. Gold is a pure substance.

Qualitative Property

Qualitative properties are properties that are observed and can generally not be measured. An example of a qualitative property would be your five senses.

Quantitative Property

Any property that uses numbers to describe a sample of matter. An example of a quantitative property would be length, width, height, etc.

Solubility

the quantity of a particular substance that can dissolve in a particular solvent (yielding a saturated solution). We can use solubility by watching sugar dissolve in water.

State of Matter

the three states of matter are solid, liquid and gas. A ball is a solid.

Sublimation

a change directly from the solid to the gaseous state without becoming liquid. An example would be dry ice.

Valence

highest energy orbital, "shell" of atom.

Viscosity

the property of a fluid that resists the force tending to cause the fluid to flow. Honey has a high viscosity