Elements and Compounds Matter Schematic Element - An element is a substance composed of the same type of atoms (e.g. gold Au, oxygen O2). Compound - A compound is a substance made of more than one type of atom (e.g. water H2O, carbon dioxide CO2). Molecule - A molecule is the smallest particle of either an element or a compound. Inert or Noble Gases Inert or Noble Gases are unreactive gases. They do not corrode or react. Examples of Noble Gases are: He - Helium Ne - Neon Ar - Argon Kr - Krypton Xe - Xenon Rn - Radon The electron rings of these unreactive gases are full, therefore they become stable. Ions (Charged Atoms) When atoms react, they may either gain or lose electrons. Electrons have a negative charge. An atom gaining or losing electrons will get an overall charge. Elements and Compounds An Atom Atom - smallest unit of all matter, that is composed of 3 sub-atomic particles called protons, electrons and neutrons Proton - the heavy positively-charged particle in the nucleus of an atom Electron - the very light negatively-charged particle that orbits the nucleus of an atom Neutron - the heavy uncharged particle in the nucleus of an atom Atom Diagram Uncharged or unreacted atoms have the same number of positive protons and negative electrons. Approximate size of atoms - Millions of atoms could fit on the sharp point of a needle. Also, if you imagine that an atom is the size of an oval, a proton and a neutron would be the size of footballs in the middle of the oval, and the electron would be the size of a rice grain racing around the running lane. Atomic Number and Atomic Mass An Example from the Periodic Table Atomic Number Diagram Atomic Number - the number of protons in an unreacted atom Mass Number - the number of protons and neutrons together Atomic Diagrams Protons and neutrons are in the nucleus. Protons are p+ Neutrons are n Electrons orbit the nucleus in electron levels or rings. Electrons are e– A limited number of electrons are situated in each electron ring. First ring - maximum of 2 electrons Second ring - maximum of 8 electrons Third ring - maximum of 8 electrons Fourth ring - maximum of 18 electrons Electron rings close to the nucleus are filled first. Elements and Compounds Matter Schematic Element - An element is a substance composed of the same type of atoms (e.g. gold Au, oxygen O2). Compound - A compound is a substance made of more than one type of atom (e.g. water H2O, carbon dioxide CO2). Molecule - A molecule is the smallest particle of either an element or a compound. Positive Ions are atoms that have lost electrons (e.g. sodium Na1+) Negative Ions are atoms that have gained electrons (e.g. chlorine Cl1–) In chemical reactions, atoms tend to gain or lose electrons to resemble the electron numbers of the stable Noble Gases. Covalent and Ionic Compounds Covalent Compound- a compound where electrons are shared between the atoms (e.g. carbon dioxide CO2) Ionic Compound - a compound formed from the attraction between positive and negative ions. For example in the ionic compound sodium chloride NaCl, the chlorine ion (Cl1–) gains one electron that was given by the sodium ion (Na1+). Common Elements and Symbols to Learn Element Symbol Element Name Element Symbol Element Name H Hydrogen Mn Manganese He Helium Fe Iron Li Lithium Co Cobalt C Carbon Ni Nickel N Nitrogen Cu Copper O Oxygen Zn Zinc F Fluorine Br Bromine Ne Neon Ag Silver Na Sodium Sn Tin Mg Magnesium I Iodine Al Aluminium Ba Barium Si Silicon W Tungsten P Phosphorus Pt Platinum S Sulphur Au Gold Cl Chlorine Hg Mercury Ar Argon Pb Lead K Potassium Cr Chromium Ca Calcium Ti Titanium Pu Plutonium U Uranium
Posted on: Mon, 07 Jul 2014 11:34:40 +0000
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