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Periodicity & States of Matter By: Dr. Pomajevich
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Periodicity & States of MatterBy: Dr. Pomajevich

The Periodic TablePeriodic table continuedPeriodic Table - Organizes many facts and trends in chemical reactivityBased upon electronic configurations of the elementsSimilarities in electronic properties lead to similarities in chemical reactivity and structurePhysical PropertiesElement - a substance that cannot be decomposed into simpler substances by chemical or physical means.Atomic radius (r) is measured as half the distance between neighboring nucleiAtomic radii increases down a group and decreases across a periodPhysical Properties ContIonic RadiusPositive ions are smaller than their parent ions, while negative ions are smaller than their parent ionsThe ionic radii increase down a group as the number of electron shells increase.Ionization EnergiesElectrons are exchanged in many chemical reactions. [i.e., A gives electron(s) to B] Ionization Energy (IE) measures how strongly an atom holds on to its electrons (the minimum energy necessary to remove an electron from the ground state of an isolated gaseous atom).I1 < I2 < I3 (increasing positive charge on atom). Very sharp increase in IE when an inner shell (core)electron is removed. Within each period, I1, generally increases with increasing atomic number Within each group, IE generally decreases with increasing atomic number (bigger atoms).

ElectronegativityThe measure of an elements atoms ability to attract electrons in a covalent bondIncreases from left to right across a period and decreases down a groupIncreased nuclear charge results in and increased attraction between the nucleus and its bond electrons.

Melting PointsDepend on type of bonding and structure of an elementMelting points decrease down group 1, most of these are metallic structuresMelting points increase down group 7, these are held together by van der Waals intermolecular forcesGenerally rise across a period and reach a maximum at group 4Chemical PropertiesGroup 0 - Noble GasesColorless GasesAre Monatomic, so they exist as single atomsAre very unreactive Group 1 - Alkali MetalsAre all silvery metals that are too reactive to be found in natureGood conductors, low densitiesWhen they react with water they produce hydrogen and the metal hydroxideGroup 7 - HalogensDiatomic molecules (come in pairs)Have colorVery reactive non-metals who's reactivity decreases down the groupKnown as halogens ContinuedHalogens react with group 1 metals to form ionic halidesMost vigorous reactions occur between elements that are farthest away from each other on the periodic tableBonding of Period 3 oxidesKnown as transition metals Ionic compounds are generally formed between metal and non-metal elements Covalent bonds normally form between two non-metals

ContinuedThe oxides become more ionic down a group as the electronegativity decreases.Acid-Base properties of the oxides are linked to their bondingMetallic elements, which form ionic oxides are basic; non-metal oxides, which are covalent, are acidicTrends across Period 3Chlorides - demonstrate similar periodic patterns in their chemical and physical properties Tend to be covalent instead of ionicContinuedChlorine reacts slowly with water in a reversible reaction to produce of hydrochloric acid and chloric acidKnow as a disproportional reaction as chlorine is both oxidized and reduced First-row d-block elementsHave helps us advance technologicallyWe use strength of steel and its alloy steel to construct buildings and so onhigh electrical and thermal conductivityhigh melting point malleablehigh tensile strength ductilePhysical propertiesChemical PropertiesForm compounds with more than one oxidation number form a variety of complex ionsForm colored compounds Act as catalysts Colors of Transition MetalsColor of transition metals can be related to presence of partially filled d-orbitals Transition metals absorb light as d-orbitals split into two sub levels Different allowances of visible light create different colorsTransition metals as catalystsHeterogeneous - the catalyst is in a different state from the reactantHomogeneous - catalysts are in same state of matter as the reactant