Question | Answer |
Chemical Reactions | a process in which atoms of different elements can combine/ decompose to make new compounds,atoms can be exchanged or transferred and gain or lose electrons |
Elements are not...? | transmuted during a reaction |
Evidence of Chemical Change | heat,light, color change,gas, and formation of precipitate |
Chemical Equations are | a shorthand way of describing a reaction |
Energy Symbols | D=Heat, Hn=light, shock= mechanical, elec- electrical |
In balanced chemical equations | The # of atoms of each element in reactants = the # of atoms in products |
In writing balanced equations | you
1. Write a skeletal equation by writing the formula of each reactant and product
2. Count the number of atoms of each side of the equation(Poly ions sometimes = 1 element)
3.Pick an element to balance |
How do you pick which elements to balance first | if an element is found in only one compounds on each side, balance it first, balance metals before non-metals, if an element is free on either side of the equation balance it last |
Synthesis/Combination | A + B = AB ( Two or more reactants combine to form one product) |
Decomposition | AB = A +B ( One substance splits into two or more simpler substances) |
Single Displacement | A + BC = AC +B ( One element takes place of another element) |
Double Displacement | AB + CD = AD +CB ( Two elements in the reactants exchange places) |
Aqueous Solutions | dissolving chemicals in water reacts faster, water separates the chemicals into individual molecules or ions, free-floating particles come in contact more frequently so the reaction speeds up |
Dissociation | when ionic compounds dissolve in water the anions and cations are separated from each other |
Dissociation of Polyatomic Ions | the groups stay together as one functioning ion |
Strong electrolytes | all the electrolyte molecules or formula units are separated into ions. |
In weak electrolytes | a small percentage of the molecules are separated into ions. |
In nonelectrolytes | none of the molecules are separated into ions. |
Types of Electrolytes | Salts = Water soluble ionic compounds.
Acids = Form H+1 ions and anions in water solution.
Strong acid = strong electrolyte, weak acid = weak electrolyte.
Bases = Water-soluble metal hydroxides.
Increases the OH-1 concentration. |
precipitation reactions | If a chemical reactions between ions in aqueous medium result in insoluble salts, and the insoluble salt will come out of solution as a precipitate. |
Are all ionic compounds, salts , water soluble | no |
CO32-, S2-, PO43-, OH- are soluble with | NH4+, Li+, Na+, K+ |
Cl-, Br-, R are not soluble with | Ag+, Pb12+, Hg22+ |
SO42- | Ba2+, Pb2+, Ca2+, Sr12+ |
Molecular equations are | Equations that describe the chemicals put into water and the products formed. |
complete ionic equations are | Equations that describe the actual dissolved species in water |
net ionic equation is | An equation in which the spectator ions are removed |
Properties of Acids are | sour taste, react with active metals, are corrosive, react with carbonates, and react with bases to form ionic salts |
Properties of Bases are | A.k.a. alkali's.
Taste bitter.
Feel slippery.
Change color of litmus and vegetable dyes.
Different color than acid.
Litmus = blue.
React with acids to form ionic salts.
And often water.
Neutralization. |
neutralization reactions are | acid-base reactions, The H+1 from the acid combines with the OH-1 from the base to make water, and The cation from the base combines with the anion from the acid to make the salt. |
Gas Evolution Reactions | Reactions in which one of the products escapes as a gas are called gas evolution reactions, Some reactions directly form a gas from the exchange of ions, In other reactions, the decomposition of one of products result in a gas and water. |
Oxidation–reduction reactions are | The element that loses electrons in the reaction is oxidized.
The substance that gains electrons in the reaction is reduced.
Oxidation and Reduction are simultaneous. |
Combustion Reactions | Combustion reactions: Reactions in which O2 is consumed by another substance.
Always release heat and/or other forms of energy.
Produce one or more oxygen-containing compounds. |
Gain of Oxygen
Loss of Oxygen | Oxidation
Reduction |
Gain of Hydrogen
Loss of Hydrogen | Reduction
Oxidation |