Vocabulary

• Atoms: The smallest unit of matter which still retains the properties of the element.
• AMU: Atomic mass unit, a mass unit based on the mass of the carbon-12 isotope.
• Anions: Negative ions, generally happens when elements gain electrons to fill the valance shell. Non-metals generally become anions.
• Atomic Mass: The mass of one mole of an atom.
• Atomic Number: The number of protons in the nucleus of an atom. The periodic table is organized by the atomic number.
• Balanced Chemical Equation: The chemical equation after coefficients have been added which shows the number of each type of atom in the reactants is equal to the number in the products. Equations must be balanced due to the law of conservation of mass.
• Bohr Model: The model of an atom which gives the nucleus in the center of the atom surrounded by electrons in orbit.
• Bond Polarity: Now equal, electrons are shared.
• Categories: Areas of the periodic table in which elements with similar properties reside, an example would be the non-metals are located in the upper right, the metals to the lower left, and the metalloid on the stair-step line which divides them.
• Cations: Positive ions, generally happen when electrons are lost to reach a full valance shell of electrons. Metals usually become cations.
• Charged: An atom becomes charged when it has lost or gained electrons. Its charge occurs to reach a state with a filled valance shell of electrons.
• Chemical Bonds: Elements form chemical bonds in order to achieve a filled valance shell of electrons. They may form bonds by becoming charged and attaching due to electrostatic charge (one positive one negative) called an ionic bond, or by sharing electrons called a covalent bond.
• Chemical Equations: The representation of a chemical reaction. The form is reactants yield products.
• Chemical Formula: The representation of a chemical compound using symbols to represent elements.
• Chemical Properties: How an element will react with other elements or compounds.
• Chemical Reaction: The process which occurs when substances convert into other substances. Usually chemical reactions are signaled by formation of a solid (precipitate), evolution of a gas (bubbles), energy changes (heat given off or taken in), or sometimes changes in color.
• Coefficient: Numbers placed in front of the reactants or products in a chemical reaction. The coefficients are placed in order to show matter was conserved in the chemical reaction.
• Covalent bonds: Bonds in which electrons are shared between two atoms. Covalent bonds occur between two non-metals.
• Electron: The subatomic particle located outside the nucleus. It has a negative charge and an insignificant mass.
• Electron Cloud: The area surrounding the nucleus where electrons reside.
• Electron Configuration: A representation of the arrangement of electrons around the nucleus of the atom (the complete address of the electron).
• Electron-Dot Diagram: A representation of an atom in which the nucleus and core electrons are given by the element symbol and the valance electrons are shown as dots surrounding the symbol. This type of diagram is useful in demonstrating how elements will react together.
• Electrostatic Attraction: Attraction due to difference between charge (positive and negative) between two particles.
• Elements: The basic components that matter is made from. There are approximately 112 elements from which all matter is made. Composed of a single type of atom.
• Energy: The ability to do work or cause a change.
• Energy Levels: Layers of electrons. When electrons change energy levels light is given off.
• Groups: Columns in the periodic table. The groups or families have similar charge and similar chemical properties and reactivity. The most important groups to know are the alkali metals, alkaline earth metals, transition metals, halogens, and noble gases.
• Ionic Compounds: Chemical compounds formed from the difference in charge. A positively charged cation is attracted to a negative anion. Metal + nonmetal.
• Law of Conservation of Mass: In any chemical reaction, matter cannot be created or destroyed.
• Matter: Anything that has mass and takes up space.
• Metals: Elements on the left side of the periodic table. They tend to have luster and be malleable and ductile. They also give away electrons to reach a stable noble-gas configuration.
• Molecular Compound: A compound in which electrons are shared between two atoms to give a stable valance electron configuration to both atoms. These are formed between two non-metals.
• Molecules: One unit of a molecular compound.
• Neutron: A subatomic particle located within the nucleus with a mass of 1 amu and no charge.
• Noble Gases: The family on the far right of the periodic table. They tend to not react with other elements due to their full valance shell of electrons. All elements try to have noble-gas configuration.
• Nonmetals: Elements located to the upper right of the periodic table which tend to gain electrons to fill their valance shell of electrons.
• Nucleus: The dense core of the atom which contains all of the protons and neutrons.
• Pattern (Trends): Patterns in the reactivity, density, melting and boiling point, and other properties seen in elements of the periodic table. They include electronegativity, which increases left to right across the table and decreases going down, size which decreases left to right but increases down, and ionization energy which tends to increase going across and decrease going down.
• Periodic Table: The tool chemists use to help them to understand matter and its properties. Arrangement of elements in groups with repeating charge.
• Periods: Rows going across on the periodic table.
• Polar Bonds: A bond in which electrons are pulled more closely to one element than another due to differing electronegativities. Compounds with polar bonds tend to attract other compounds with polar bonds and ionically bonded substances. Water is an example of something with a polar bond.
• Products: The right side of a chemical equation, the things you end with in a chemical reaction.
• Proton: A subatomic particle located within the nucleus with a a mass of 1 amu and a positive charge.
• Reactants: The left side of a chemical equation, the things you start with in a chemical reaction.
• Stoichiometric Relationships: The relative amounts of reactants and products in a chemical reaction.
• Subatomic Particle: Things that make up an atom. Protons, neutrons, and electrons.
• Transition Elements: Elements in groups 3-12 on the periodic table. Their charges may vary and are represented by a roman numeral in any compound name.
• Valence Electrons: Electrons in the outermost layer of the atom. Elements are most stable when they have 8 valance electrons, and they gain or lose electrons to get 8.