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Chemistry
Chemistry Vocabulary
Term | Definition |
---|---|
Matter | Anything that has volume (takes up space) and has mass |
Atom | The smallest unit of an element that has all of the properties of that element containing a nucleus within an electron cloud |
Electron Cloud | All of the area surrounding the nucleus where electrons are found |
Nucleus | The tiny very dense positively charged region in the center of an atom made up of protons and neutrons |
Electrical Charge | A form of charge designated negative positive or neutral (without charge) that is found on the subatomic particles that make up all atoms |
Proton | A positively charged subatomic particle of the nucleus of an atom that contributes to the mass of the atom |
Neutron | A subatomic particle of the nucleus of an atom that is without charge that contributes to the mass of an atom |
Electron | A negatively charged subatomic particle of the electron cloud that is involved in the formation of chemical bonds (almost negligible mass) |
Subatomic Particles | Particles that are smaller than the atom (positive negative and neutral) |
Chemical Formula | A shorthand notation that uses chemical symbols and numbers as subscripts to represent the type and number of atoms that are present in the smallest unit of the substance |
Balanced Equations | chemical reaction in which both sides of the equation contain equivalent numbers of atoms of each element. The mass and the charge must be balanced on both sides of the reaction (law of conservation of mass) |
Atomic Mass | The average mass of protons and neutrons in an element |
Nuclear Model of the Atom | A conceptual model of the atom in which a positively charged nucleus is surrounded by electrons |
Atomic Number | The number of protons in the nucleus of one atom of the element (top number) |
Valence Electrons | The electrons in the outermost energy level of an atom that influence how an element will react with other substances |
Energy Level | Shells/Orbitals Regions around the nucleus of an atom where electrons may be found |
Net Charge | The sum of negative and positive charges |
Ions | Form as a result of the loss or gain of electrons identified by the overall net charge |
Property | The physical and chemical characteristics of a substance or element |
Reactivity | Rate at which a chemical substance tends to undergo a chemical reaction significantly influenced by valence electrons of the reacting substances |
Valence Shell | The outermost shell (or shells) determine the chemical properties of the atom (group number) |
Metals | Most elements are these they are typically solid shiny malleable and good conductors |
Nonmetals | Elements typically not shiny usually a gas or brittle solid not malleable and poor conductors |
Periodic Table of Elements | A table showing the chemical elements arranged according to their atomic numbers |
Groups | The vertical columns on a Periodic Table that arrange the elements by the number of electrons that are in the outermost shell |
Period | The horizontal rows in a Periodic Table that classify the elements by the number of electron shells |
Metalloids | Elements that have properties of both metals and nonmetals sometimes referred to as semiconductors |
Noble Gases | Unreactive nonmetals in Group 18 of the Period Table |
Electron Shell | A specific area where electrons of the same energy level are found |
Element | A pure substance that cannot be separated into simpler substances by physical or chemical means |
Atomic Symbol | A one- or two-letter notation used to represent an atom of a particular element |
Subscript | A number written below and to the right of a chemical symbol that shows the number of a specific type of atom present |
Coefficient | A number placed in front of a chemical symbol or formula in order to balance the equation |
Reactants | A substance that takes part in and undergoes change during a reaction On the left side of a formula |
Products | A substance produced during a chemical reaction On the right side of the formula |
Law of Conservation of Mass | The mass of all reactants must equal the mass of all products mass is neither created nor destroyed. Balanced equation |
Mass | The amount of matter an object contains measured in grams |
Evidence of a Chemical Change | Noticeable: the four signs of a chemical reaction are: production of (1) gas (2) heat/light formation of (3) precipitate or a (4) new substance |
Substance | Elements or compounds that can only be separated or combined to make substances with new properties by means of a chemical reaction |
Endothermic | A reaction that gets cold because heat energy is absorbed from the surrounding area |
Exothermic | A reaction that gets hot as heat energy is released to the surrounding area |
Synthesis | When two elements react to form a compound. Root: to make |
Decomposition | When a compound breaks down into two substances (an element and a compound) |
Combustion | When an organic substance combines with oxygen and releases large amounts of heat and light energy |
Mechanical Change | Substances undergo a physical change. Ex. dissolving in water |
Ductile | metal made into wire easily |
Malleable | metal that can be hammered |
Insulator | nonmetal poor conductor holds heat in |
Conductor | metal heat & electricity travels through it easily |
Brittle | nonmetal cannot be hammered or made into wire because it falls apart easily |