Science Chap.7&8
Terms
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- Polyatomic Ions
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~A group of covalently bonded atoms that act as a single atom when bonding with other atoms.
~ Bonding woth polyatomic ions are covelant but they bond using ionic bonds with other atoms - Synthesis
- Two or more smaller substances combine to form one bigger, more complex substance
- Rates of Chemical Reactions
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~Kinetics is the study of reaction rates
~Collision Theory how fast a reaction occurs depends on four things
~Concentration
~Surface Area
~Temperature
~Catalyst - Surface Area
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~The greater the sirface area the faster the reaction rate
~To increase the rate of the reactoin you can break reactants into smaller pieces - Activation Energy
- Energy required for a chemical reaction to occur
- Endothermic Reaction
- Energy is absorbed
- Metallic Bonds
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~Occurs between two non-metals
~They a common electron cloud or sea of electrons
~The positive nucleus is attracted the surrounding electrons - Oxidation Number
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~The number of electron lost, gained, or shared during a chemical bond
~It is used to predict how the atoms will combine and what formula the resulting compound will be
~#1 rule the sum of the oxidation numbers must be zero - Catalyst
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~A substance that increases the rate of a reaction but is not itself changed by the reaction
~ It causes the activation energy needed to decrease
- Chemical Bonding
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~The combining of elements to form new substances.
~The electrons involved in chemical bonding are valence electrons.
~Three types of bonding Ionic, Covalent, and Metallic - Chmeical Reactions
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~Process in which the phys. and chemical properties of the original substances change as new substances with different phys. and chemical properites form
~Reactants yield products
~Energy is either abosrbed or realeased during a chemical reaction
- Temperature
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~As temperature increases the reaction rate increases
~As temperature increases the amount of collisions increase as does the force with which the they collide making a greater percentage of the collisions "Effective Collision" - Ionic Bonding
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~Bonding that involves the transfer of electrons
~Form ions which are charged atoms
~Ionic bonds tend to from between metals and non-metals - Types of chemical reactions
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~There are four types
~Synthesis
~Decomposition
~Single Replacement
~Double Replacement - Crystals
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~The placement of ions in an ionic compound results in a regular, repeating. pattern called a crystal lattice.
~Crystals have high melting points and are very stable - Electron Affinity
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~The tendency of an atom to gain electrons
~As you go across the periodic table the electron affinity increases
~Flourite has the highest electron affinity
- Concentration
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~The higher the concentration the greater the reaction rate
~ In a reversible reaction if the reactants concentration is increased then the reaction increases in the forward direction. If the products concentration increases then the reverse reaction's rate increases. - Decomposition
- Breaking a complex compound into two or more substances
- Molecules
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~Combination of atoms formed by a covalent bond
~Molecules usually have high melting points expcept for sand and graphite they are network solids - Double Replacement
- The compounds switch partners
- Exothermic Reaction
- Energy is released
- Covealent Bond
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~The sharing of electrons between two non-metals.
ex. H2O - Single Replacement
- An element replaces one of the elements in a compound