Grade 11 chemistry - the nature of chemistry

Matter

Anything that has mass and takes up space

Empirical knowledge

Knowledge that comes from investigation and Observation

Theoretical knowledge

Knowledge that explains scientific observations

Theory

An explanation or model based on observation, experimentation and reasoning.

Atom

The smallest particle of an element

Electron

A negatively charged particle in an atom or ion

Proton

A positively charged particle in the atoms nucleus

Neutron

A neutral particle in an atoms nucleus

Energy level

A theoretical sphere around an atom where electrons exist; electron orbit

Valence shell

The outermost energy Lebel or orbit of an atom or ion

Valence electron

An electron in the outermost energy level or orbit

Atomic number

The unique number of protons in one atom of an element

Mass number

The sum of the protons and neutrons in the nucleus of an atom

Atomic mass unit

A very small unit of mass defined as 1/12 the mass of a carbon-12 atom; unit symbol u

Full or stable octet

An electron arrangement where the valance shell is filled with 8 valence electrons (2 for hydrogen and helium)

Octet rule

A generalization stating that when atoms combine, they tend to achieve 8 valence electrons

Ion

A charged entity formed when an atom gains or loses one or more electrons

Cation

A positively charged ion formed by the removal of one or more electrons from the valence shell of a neutral atom

Valence

The charge of an ion; the combining capacity of an atom determined by the number of electrons that it will lose, add or share when it reacts with other atoms

Anion

A negatively charged ion formed by the addition of one or more electrons to a neutral atom

Multivalent

The property of having more than one possible valence

Polyatomic ion

An ion, made up of more than one atom, that acts as a single entity

Isotope

A form of an element in which the atoms have the same number of protons as all other forms of that element, but a different number of neutrons

Isotopic abundance

The percentage of a given isotope in a sample of an element

Mass spectrometer

A measuring instrument used to determine the mass and abundance of isotopes

Radioactive decay

The spontaneous disintegration of an unstable isotopes

Nuclear radiation

Energy or very small particles emitted from the nucleus of a radioisotope as it decays

Alpha particle

A product of nuclear decay emitted by certain radioisotopes; a positively charged particle with the same structure as the nucleus of a helium atom

Beta particle

A product of nuclear decay emitted by a certain radioisotopes; a negatively charged particle identical to an electron

gamma ray

A form of high energy electromagnetic radiation emitted by certain radioisotopes

Radioisotope

An isotope that spontaneously decays to produce two or more smaller nuclei and radiation

Radioactive

Having the potential to emit nuclear radiation upon decay

Atomic mass

The weighted average of the masses of all the naturally occurring isotopes of an element

Hydrogen

a unique element with many physical properties of non metals but chemical properties of metals

Alkali metals

Soft silver-coloured elements; solids at room temperature; exhibit metallic properties; react violently with water to liberate hydrogen gas; react with halogens to form compounds such as sodium chloride, NaCl(s); stored under oil or in a vacuum to prevent reaction with air

Alkaline earth metals

Light, very reactive metals; solids at room temperature; exhibit metallic properties; react with oxygen to form oxides with the general chemical formula, M0(s); all except beryllium will react with hydrogen to form hydrides; react with water to release hydrogen

Transition metals

Exhibit a range of chemical and physical properties; strong, hard metals with high melting points; good conductors of electricity; variable reactivity; form multivalent ions; many react with oxygen to form oxides; some react with acids to release hydrogen gas

Metalloid

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

Group

A column of elements in the periodic table; sometimes referred to as a family

Period

A row in the periodic table

Periodic law

A rule, developed from many observations, stating that when the elements are arranged in order of increasing atomic number, their properties show a periodic recurrence and gradual change

Lanthanides

Elements with atomic numbers 57 to 70

Actinides

Elements with atomic numbers 89 to 102

Transuranic elements

Synthetic (not naturally occurring) elements with atomic numbe 93 or greater (beyond uranium)

Noble gases

Gases at room temperature; low melting and boiling points; extremely un reactive, making them especially intresting to chemists; krypton, xenon and radon reluctantly for compounds with fluorine; radon is radioactive

Halogens

May be solids, liquids, or gases at room temperature; exhibit non-metallic properties —not lustrous and non-conductors of electricity; extremely reactive, especially fluorine; react easily with hydrogen and metals

Representative elements

Both metals and nonmetals from group 1 2 and 13 to 18; may be solids, liquids or gases at room temperature; many form colourful compounds

Atomic radius

A measurement of the size of an atom, usually expressed in picometers (pm); the distance from the centre of an atom to the outermost electrons

Effective nuclear charge

The net force experienced by an electron in an atom due to the positively charged nucleus

Ionic radius

A measurement of the size of an ion, usually expressed in picometres (pm); the distance from the centre of an ion to the outermost electrons

Ionization energy

The quantity of energy required to remove an electron from an atom or ion in the gaseous state

Electron affinity

The energy change that occurs when an electron is added to a neutral atom in the gaseous state