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Chemistry_Terms
| Term | Definition | |
|---|---|---|
| Molecule | Two or more atoms connected by chemical bonds. A molecule is the smallest unit of a compound. | |
| Element | One of 118 or so substances that can not be broken down any further into simpler substances. 92 are naturally occurring, and the remainder are made in the laboratory. The smallest unit of an element is an atom. | |
| Compound | A substance whose molecules are made up of different atoms. | |
| Mixture | A combination of two or more substances. | |
| Solution | A combination of two substances, one of which is a liquid. The other substance (liquid, solid or gas) is fully dissolved in the liquid. | |
| Heterogeneous Mixture | A mixture with different components that can be identified by eye | |
| Homogeneous Mixture | A mixture with different components that looks uniform to the naked eye | |
| Atomic Number | The number of protons in an atom The number of electrons in an atom Number of protons = number of electrons in a neutral atom | |
| Atomic Mass | The number of protons PLUS the number of neutrons (the massive particles) that make up the nucleus | |
| Electron | A light negatively charged sub-atomic particle that orbits around the nucleus | |
| Proton | A heave positive charged sub-atomic (smaller than an atom) that lives in the nucleus | |
| Neutron | A heavy neutral sub-atomic (smaller than an atom) particle that lives in the nucleus | |
| Chemical Change | A chemical change means that a chemical reaction has taken place. Evidence of a chemical change includes a) the production of gas b) a change in colour c) change in temperature d) precipitate formed e) any explosion!! | |
| Physical Change | A change of state. Any mixture that is created. A solid that dissolves in liquid Ex: boiling water, making trail mix, dissolving Kool-Aid in water | |
| Conservation of Mass | The total mass of the reactants = the total mass of the products The number of atoms of an element in the reactants = the number of atoms of same element in the products | |
| Conservation of Charge | The total number of electrons stays constant (chemical reactions, electric circuits) | |
| Conservation of Energy | Energy is neither created nor destroyed. Energy can be converted to different forms. Ex: | |
| Chemical Reaction | Elements and/or compounds combine and form one or more new substances. | |
| Periodic table of Elements | A table or chart that organizes all the elements and gives basic information such as atomic number, and atomic mass | |
| Isotope | An atom of an element that has more (or fewer) neutrons in the nucleus | |
| Ion | At atom that has gained one or more electrons or has given up one or more electrons | |
| Positive Ion | At atom that has given up (lost) one or more electrons | |
| Negative Ion | An atom that has gained (taken) one or more electrons | |
| Nucleus | The central, heavy and very dense part of an atom. The nucleus contains protons and neutrons | |
| Orbit or Shell | A location of electrons around a nucleus. The first orbit (closest to the nucleus) can hold at most 2 electrons. The next orbit can hold at most 8 electrons. The next orbit can hold at most 8 electrons *ALERT - this is for grade 9 purposes. | |
| Valence (Outer) Shell | The outermost orbit or shell of an atom | |
| Noble Gases | Elements in group 18. Each element has a FULL valence or outer shell. Ex: He, Ne, Ar | |
| Alkali Metals | Elements in group1. Each element has only one electron in its valence or outer shell. Ex: Na | |
| Alkali Earth Metals | Elements in group 2. Each element has only two electrons in its valence or outer shell. Ex: Ca | |
| Halogens | Elements in group 17. Each element has room for one more electron in its valence or outer shell. Ex: Cl | |
| Ionic Bond | A chemical bond made by the transfer of electron(s) from one atom to another to form positive and negative ions. The positive and negative ions then attract each other | |
| Covalent Bond | A chemical bond made by the sharing of electrons between two atoms | |
| Bohr-Rutherford Diagram | A diagram that shows the electron configuration (how the electrons are distributed) of an atom as well as the number of neutrons and protons in its nucleus | |
| Kinetic energy | The energy of movement (or motion) | |
| Sublimation | State change from solid directly to gas | |
| Deposition | State change from gas directly to solid | |
| Boiling | State change from liquid to gas | |
| Condensation | State change from gas to liquid | |
| Freezing | State change from liquid to solid | |
| Melting | State change from solid to liquid | |
| Atom | The most basic unit of a chemical element. Elements can occur in nature as molecules at room temperature. Ex: Chlorine gas, Oxygen gas, Hydrogen gas |