Basic Chemistry 2

Terms	Definitions
meniscus	when water is in a container, the curve of the water
volume	the amount of space occupied by an object
mass	the amount of matter in an object
gram	the SI unit for expressing mass
matter	anything that has volume and mass
density	Mass per unit volume, the amount of matter in a given space, a physical property, used to identify substances because it is always the same at a given pressure or temperature
chemical change	occurs when one or more substances are changed into entirely new substances with different properties
physical property	a characteristic of matter that can be observed or measured without changing the identity of the matter
physical change	change that affects only the physical properties of a substance
chemical property	property of matter that describes its ability to change into new matter with different properties
thermal conductivity	is the rate at which a substance transfers heat
Ductility	the ability of a substance to be pulled into a wire
malleability	the ability of a substance to be rolled or pounded into thin sheets
weight	measure of the force of gravity on an object
matter	anything that has volume and mass
physical property	a characteristic of matter that can be observed or measured without changing the identity of the matter
physical change	change that affects only the physical properties of a substance
chemical property	property of matter that describes its ability to change into new matter with different properties
solubility	the ability of one substance to dissolve in another at a given temperature and pressure
Group 1-Alkali Metals	Metals, 1 electron, very reactive, soft; silver-colored;shiny; low density.
Group 2 Alkaline-earth Metals	Metals, 2 electrons, very reactive, less reactive than alkali metals, Silver-colored; more dense than alkali metals
Groups 3-12 Transition Metals	Metals, 1 or 2 electrons, less reactive than alkaline-earth metals, shiny good conductors of thermal energy and electric current; higher densities and melting points (except for mercury) than elements in groups 1 and 2
Lanthanides and Actinides	Lanthanides- shiny reactive metals. Actinides radioactive, means they are unstable
Group 13 Boron Group	1 metalloid and 4 metals, 3 electrons ; reactive; solid at room temperature
Group 14 Carbon Group	1 nonmetal, 2 metalloids, and 2 metals, 4 electrons, reactivity- varies among the elements, solid at room temperature
Group 15 Nitrogen Group	2 nonmetals, 2 metalloids, and 1 metal, 5 electrons, reactivity- varies among the elements, all but nitrogen are solid at room temp.
Group 16 Oxygen Group	3 nonmetals, 1 metalloid, and 1 metal, 6 electrons, reactive, all but oxygen are solid at room temp.
Group 17 Halogens	nonmetals, 7 electrons, very reactive, poor conductors of electric current; react violently with with alkali metals to form salts; never found uncombined in nature
Group 18 Noble Gases	Nonmetals, 8 (2 for helium) unreactive, colorless oderless gasses at room temp.
Hydrogen	1 electron, reactive, colorless, odorless gas at room temp., low density; reacts explosively with oxygen
Group	Column of elements
Chemical Bonding	the joining of atoms to form new substances
Valence electrons	the electrons in the outermost energy level
Ionic bond	the force of attraction between oppositely charged ions
Ion	charged particles that form during chemical changes when one or more valence electrons transfer from one atom to another
Covalent bond	the force of attraction between the nuclei of atoms and the electrons shared by the electrons
Molecule	a neutral group of atoms held together by covalent bonds
Metallic bond	the force of attraction between a positively charged metal ion and the electrons in a metal.
Electron clouds	regions inside an atom where electrons are likely to be
Atomic number	The number of protons in the nucleus of an atom
Isotopes	atoms that have the same number of protons but have different numbers of neutrons
Mass number	the sum of the protons and neutrons in an atom
Acids	a compound that increases the number of hydrogen ions when dissolved in water, tastes sour, corrosive, turns blue litmus paper red
Activation energy	the energy needed to start a chemical reaction
atoms	the smallest particles of an element that retain the properties of the element
atomic mass	the mass of an atom
base	any compound that increases the number of hydroxide ions when dissolved in water, tastes bitter, feels slippery, turns red litmus paper blue
boiling point	the temperature at which a liquid boils
Catalyst	a substance that speeds up a chemical reaction without being permanently changed
Chemical equation	describes a chemical reaction using formulas, symbols and coefficients
Chemical formula	indicates the chemical makeup by showing how many of each kind of atom is present in a molecule
Chemical symbol	the letter or letters that represent an element on the periodic table
Colloid	a mixture in which the particles are dispersed throughout the substance, but are not heavy enough to settle out. Jello and whipped cream.
Compounds	pure substances composed of two or more elements chemically combined. Each compound has a unique set of physical and chemical properties that are different from properties of elements that compose it.
Concentration	A measure of the amount of solute dissolved in a solvent.
Condensation	a change of state from a gas to a liquid
Sublimation	a change of state from a solid directly to a gas
Vaporization	a change of state from a liquid to a gas: could be boiling or evaporation
filtration	a substance with pores through which a gas or a liquid is passed to separate out floating matter
Evaporation	vaporization that occurs at the surface of a liquid below its boiling point
mixture	a combination of two or more substances that are not chemically combined; can be separated by physical means- pizza
element	a pure substance that cannot be broken down into anything simpler by physical or chemical means; has a unique set of physical properties
Hydrolysis	breaking down a chemical by splitting a bond and adding water
distillation	a process that separates a mixture based on the boiling points of the components
States of Matter	physical forms in which a substance can exist. The state of matter of a substance is determined by how fast the particles move and how strongly the particles are attracted to each other
Exothermic changes	releases energy and is the product of a chemical equation
Endothermic changes	changes that absorb energy and can be written as a reactant in a chemical equation
Solution	a mixture that appears to be a single substance but is composed of particles of two or more substances that are distributed evenly amongst each other
Homogeneous solutions	have the same appearance and properties throughout the mixture-- salt water, air, steel
tarnish	a film of chemically changed material on the surface of a metal like silver
pH scale	pH of a solution is a measure of the hydronium ion concentration in the solution; the scale is used to describe how acidic or basic a solution is
Metals	elements that are shiny and are good conductors of thermal energy and electric current; most metals are malleable and ductile
Metalloids	elements that have properties of both metals and non-metals; sometimes referred to as semi-conductors
Non-metals	elements that are dull and are poor conductors of thermal energy or electric current
Precipitate	a solid formed in a solution as a result of a chemical reaction
Substance	a physical material from which something is made; a pure substance is a substance in which there is only one type of particle
Indicators	a substance used to show visually (as by a change in color) the presence of an acid or a base in a solution
Suspension	a mixture in which particles of a material are dispersed throughout a liquid or a gas, but are large enough so they can settle out
Solute	the substance that is dissolved in another substance
Solvent	the substance in which the solute is dissolved
Products	the substances formed from a chemical reaction
Reactants	the starting materials in a chemical reaction
Solids	have a definite shape and volume
Liquids	have a definite volume, but not a definite shape
Gases	do not have a definite shape or volume. A gas takes the shape and volume of its container
Salt	an ionic compound formed from the positive ion of a base and the negative ion of an acid
Equalibrium	The definition of chemical equilibrium is the point at which the concentrations of reactants and products do not change with time. It appears as though the reaction has stopped but in fact the rates of the forward and reverse reactions are equal so reactants and products are being created at the same rate.
Protons	positively charged particles of the nucleus of an atom
Electrons	small negatively charged particles located throughout an atom in an electron "cloud"
Neutrons	particles in the nucleus of an atom that have no charge
Nucleus	the small, dense, positively charged center of an atom. Contains most of the atoms mass.
Periodic Table of the Elements	an arrangement of elements in a table in order of increasing atomic mass
Periodic Law	states that the chemical and physical properties of elements are periodic functions of their atomic number
Groups	columns on the periodic table. Elements in the same group often have similar chemical and physical properties
Periods	the horizontal rows of elements on the Periodic Table. The properties of elements in a row follow a repeating pattern
Law of the Conservation of Energy	States that energy is neither created or destroyed
Triple beam balance	used to measure the mass of an object
Melting	change of state from a solid to a liquid. Melting point is a characteristic property and it is an endothermic reaction because energy is absorbed
Freezing	change of state from liquid to solid; freezing and melting occur at the same temperature. It is an exothermic reaction because energy is removed.
Inhibitor	a substance that slows down or stops a chemical reaction - preservatives
Ionic compound	can be formed by a reaction of a metal with a non-metal
Covalent compound	composed of elements that are covalently bonded and consist of independent particles called molecules
Subscript	the number written below and to the right of a chemical symbol in a formula. It indicates how many atoms of that element are in the molecule.
Decomposition reaction	a single reactant breaks apart into two or more simpler products
Synthesis reaction	the reactants form a single product
Single-replacement reaction	a more reactive element takes the place of a less reactive element in a compound
Double-replacement reaction	ions in two compounds switch places
Surface area	The amount of exposed surface