Welcome to the grade 9 chemistry vocabulary list! Below ...

Welcome to the grade 9 chemistry vocabulary list! Below you will find a comprehensive list of the key ideas and concepts needed to successfully navigate our chemistry unit. You are required to know all these definitions, and we may add other definitions and key words as we progress through the unit. I've organized the list according to the major topics from the unit.

Atomic Theory

Atomic Theory of Matter

Atom

Nucleus (plural: nuclei) Valence shell Proton Electron Neutron Isotopes Ions

1. All matter is made of atoms. 2. All atoms of an element are identical in mass and properties. 3. Compounds are formed by combining 2 or more kinds of atoms. 4. Chemical reactions are rearrangements of atoms. Source:

the smallest particle of an element which can exist by itself. A typical atom consists of a nucleus of protons and neutrons with electrons orbiting this nucleus. An atom is the defining structure of an element. Source:

the center of an atom, containing protons and neutrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons Source:

the outermost energy level where electrons orbit around the atomic nucleus Source: ll.htm

A positively-charged particle in the center of atomic nuclei, with a relative mass of 1 amu; the number of protons determines the chemical identity of an atom Source:

The lightest subatomic particle known. It carries a negative charge, which is considered the basic unit of electric charge. Electrons orbit around the atomic nucleus in shells of different energy levels. Source:

A particle in the center of atomic nuclei, which have no electrical charge. Neutrons have a relative mass of 1 amu, like protons; however, atoms of the same element may have different numbers of neutrons. Source:

Forms of an element with the same number of protons but different numbers of neutrons in the atomic nuclei. Isotopes of an element have the same chemical properties but different atomic masses. Source:

Forms of an element which have an electrical charge because they have either gained or lost electrons. Ions which have gained electrons have a negative charge and are called anions. Ions which have lost electrons have a positive charge and are called cations. Source:

Anion Cation Octet Rule Atomic symbol Atomic number (Z) Atomic mass (A) Atomic Mass Unit (AMU) Electron configuration

Electron shell

ounds/ionicrev1.shtml

A negatively charged ion, produced when one or more electrons are added to an atom. Source:

A positively charged ion, produced when one or more electrons are lost from an atom. Source:

The tendency of atoms to gain or lose electrons in order to have 8 electrons in their valence shell. The number of electrons gained or lost determines the charge of the resulting ion. Source:

A one-letter or two-letter abbreviation for a specific element. The first letter of symbols is always capitalized, but the second letter of 2-letter symbols is never capitalized. Source:

the number of protons in one atom of a particular element, abbreviated as the letter `Z' Source:

The combined number of neutrons and protons in the atomic nuclei of an element, abbreviated by the letter `A'. Source: massnumber.htm

The unit of measurement for subatomic particles. It is based on the average mass of a proton or neutron, so that the mass of 1 proton = 1 amu. Source:

The way that electrons are arranged in different energy levels around the nucleus of an atom. The energy levels correspond with electron shells in the Bohr model of atoms. Source: Armstrong, Rick, Kevin Gaylor, and Jenny Sharwood. Chemistry 4/5 for the International Student. South Melbourne, Vic.: Cengage Learning, 2010. Print.

Electrons are arranged in shells at different distances around the nucleus.Each shell represents a different energy level, with the lowest-energy shell closest to the atomic nucleus. Each shell may hold a maximum number of electrons, arranged in pairs as often as possible. Source: dic_table/electronsrev1.shtml

Periodicity and the Periodic Table

Periodicity

Repeating trends that are seen in elements' properties, and which can be predicted based on an element's position in the periodic table. The major properties we will study are electronegativity, electron affinity, atomic radius, and ionization energy. Source: he-Periodic-Table.htm

Group

A column of elements in the periodic table, sometimes also called a family of elements. Each group has common chemical and physical characteristics based on the elements' electron arrangements. Source:

Period

A row of elements in the periodic table. Periods are based on the number of energy levels where electrons orbit atomic nuclei. Source:

Metal

a substance (such as gold, tin, or copper) that usually has a shiny appearance, is a good conductor of electricity and heat, can be melted, and is usually capable of being shaped. Source:

Nonmetal

Elements which do not exhibit metallic properties, generally located in the upper righthand corner of the Periodic Table. Nonmetals usually gain electrons in ionic bonds, or they may share electrons with other nonmetals in covalent bonds. Source:

Metalloid

Metalloids are the elements found along the stair-step line that distinguishes metals from nonmetals. Metalloids have properties of both metals and nonmetals. Some are semi-conductors. Source:

Alkali metals

The elements in the first group (Group 1) on the left side of the periodic table. Properties of Alkali metals are:

highly reactive always found bonded with other elements 1 valence electron can be easily donated - become +1 cations form ionic bonds with nonmetals malleable and ductile extremely soft silvery color good conductors low boiling and melting points explosive reactions with water Source: _Group_Elements/Group__1%3A_The_Alkali_Metals

Alkaline Earth metals

The elements in Group 2 of the periodic table. Properties of Alkaline Earth

Transition metals

Noble Gases Halogens Diatomic elements

metals: reactive, but less so than Alkali metals malleable soft silver color conductors 2 valence electrons are lost to become +2 cations form ionic bonds with nonmetals never found alone in nature

Source: _Group_Elements/Group__2%3A_The_Alkaline_Earth_Metals

The elements in the center of the periodic table, from Group 3 - Group 12. They tend to lose electrons to form cations with charges from +1 to +7, and many transition metals will form several different cations (Mn, for example, may be Mn2+, Mn3+, Mn4+, Mn6+, or Mn7+. Properties of transition metals:

form coloured compounds good conductors of heat and electricity hammered or bent into shape easily less reactive than alkali metals such high melting points - but mercury is a liquid at room temperature usually hard and tough high densities

Source: rns/transitionmetalsrev1.shtml

The elements in Group 18 (the far right column) of the periodic table. They are all gases, and they are almost totally non-reactive with other elements. They have a full valence shell, so that they don't gain or lose electrons. Source: _Group_Elements/Group_18%3A_The_Noble_Gases

The elements in Group 17 of the periodic table, the halogens all have 7 valence electrons. This means they all gain 1 electron in order to fulfil the octet rule. Properties of halogens:

form anions with a 1- charge extremely reactive diatomic molecules poisonous react with metals to form salts Source:

Atoms of these elements will combine with atoms of the same element in order to form stable molecules of the element. The molecules are formed when atoms share one or more pairs of electrons. Diatomic elements are not diatomic when they bond with different elements!The diatomic elements you have to know are:

H2 N2 O2 F2

Oxygen group Nitrogen group Lanthanides Actinides

Atomic radius

Melting point Electronegativity

Cl2 Br2 I2 Source: 1B/DiatomicElements.htm

All the elements underneath oxygen in the periodic table, which have 6 valence electrons. They are less reactive than the halogens, but because they gain 2 electrons, are still fairly reactive.

All the elements under nitrogen in the periodic table (group 15), which have 5 valence electrons. They may form 3 covalent bonds, which are the strongest type of covalent bond. Nitrogen and phosphorus are important for the growth of producers. Source:

The top row of the Rare Earth metals, which are the two rows separated from the rest of the periodic table at the bottom. They dissolve in acids and tarnish easily when exposed to air. They also react with water, but slowly. Source: ition_Metals_and_Coordination_Complexes/The_Lanthanides#Properties_and_ Chemical_Reactions

The bottom row of the Rare Earth metals. All are radioactive (this is where uranium is found in the periodic table!) because their nuclei are unstable, and all are considered toxic. Most have been made synthetically and do not occur much naturally. Source: ition_Metals_and_Coordination_Complexes/The_Actinides#Common_Propertie s

The distance from the nucleus of an atom to the valence shell, where the outermost electrons orbit. One of the important trends we study in chemistry because it relates to the strength with which atoms hold onto electrons when bonding with other atoms. Atoms become smaller as we move to the right across periods because the electrons are more strongly attracted to the greater number of protons in the atomic nuclei. Atoms become larger as we move down the groups because additional electrons are added in shells further from the nuclei. Source:

The temperature at which a substance changes from a solid to a liquid. In theory, this is the same temperature at which the liquid will turn into a solid, called the freezing point. Source:

A measure of how strongly an atom holds electrons in a covalent bond. This is important in determining polarity of substances. Source:

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