CHEMISTRY REVIEW

CHEMISTRY REVIEW - CHEMISTRY TOPIC 1- THE ATOM Daltons...

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CHEMISTRY
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TOPIC 1- THE ATOM Dalton’s Atomic Theory - All elements made of indivisible atoms - All atoms of a given element are identical - Atoms of dif’t elements have dif’t masses - Compounds are formed by the combination of atoms of dif’t elements It’s not all true… Atom is not indivisible, made up of… 1. Electrons: discovered using cathode ray, negatively charged, 2. Nucleus: dense central core, positively charged contains protons and neutrons (each about 1 amu or 1.67 x 10 -24 g (electrons are about 1/1836 amu) – note carbon atom = standard mass, all masses relative to it plum pudding Bohr atom wave-mechanical model - Has orbitals : regions in which an electron of a particular amount of energy is most likely to be located - First orbital has 2 electrons, second has 8 isotope: same element, different number of electrons and thus different mass number ground state: when an electron occupies the lowest available orbitals excited state: when electrons are subjected to stimuli and temporarily move to a higher level - emits energy when it quickly returns (like fluorescent light) quantum numbers: describe electrons - principle quantum number: describes major energy level (number of level that holds electron) - second quantum number: describes sublevel: s, p, d, f (as many as number of level) - third quantum number: relates to orbitals in sublevel - in s = sphere - in p = dumbbell (x, y, z) - in levels 3 and higher: d (5 orbitals) - in levels 4 and higher: f (7 orbitals) - fourth quantum number: spin of electron, each orbital can have two electrons spinning in opposite directions Hund’s rule: must space out electrons before pairing up
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Outermost principle energy level can only have s and p orbitals After 3p, comes 4s and THEN 3d pure substance: composition same throughout sample element: cannot be broken or decomposed by chemical means (91 occur naturally) compound: two or more elements chemically combined in definite proportions by mass, has its own properties, homogenous law of definite proportion: types of atoms in a compound exist in a fixed ratio mixture: combination of two or more pure substances that can be separated by physical means, hetero or homogeneous, each component has own properties and can be separated easily solution: homogenous mixture TOPIC 2: FORMULAS AND EQUATIONS diatomic molecule: two identical atoms covalently bonded into one empirical formula: represents simplest integer ratio in which atoms combine to form a compound, always for formulas of ionic substances molecular formula: covalently bonded substances, represents actual ratio polyatomic ion: group of atoms covalently bonded together, possessing a charge hydrate: when water from some ionic solutions evaporates, solute forms a crystal lattice that binds water within the structure (called a hydrate), have a definite number of water molecules for each unit of the compound, adds mass to a compound (crystal with water molecules attached) anhydrous: substance without water Naming…
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CHEMISTRY REVIEW - CHEMISTRY TOPIC 1- THE ATOM Daltons...

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