matter
anything that takes up space and has mass
chemistry
the study of matter
physical properties
characteristics that can be observed or measured without changing chemical identity (colour, texture)
chemical properties
describe the ability of matter to react with another substance to form different substances (combustibility, lack or reactivity)
physical change
change of matter that does not alter its chemical identity or composition (freezing of water to form ice)
chemical change
change of matter that produces new substances (colour change, formation of bubbles)
atoms bond together to form…
ionic and covalent compounds
can mass be created or destroyed in chemical reaction
no
a chemical equation represents…
what happens to atoms in a reaction
pure substance
can be element or compound
compound
made up of atoms of 2 or more different elements
ionic compound
compound made up of oppositely charged ions. consists of positively charged ions, cations, and negatively charged ions, called anions.
ionic bond
strong attraction that forms between oppositely charged ions. in this, atoms lose or gain electrons to form ions that have full valence shells and are therefore more stable
covalent compound
compound that results when 2 or more atoms of non metal elements bond covalently
covalent bond
strong attraction between atoms that forms when atoms share valence electrons
molecule
particle made up of two or more atoms bonded by covalent bonds. most covalent compounds exist as molecules
elements combine with compounds to form…
new compounds and new elements
energy is required to ___ chemical bonds
break
energy is ___ when chemical bonds form
released
closed system
energy can enter or leave but not matter
open system
energy and matter can enter or leave
law of conservation of mass
in a chemical reaction, the total mass of the substances used is equal to the total mass of the substances produced
chemical equation
the representation of a chemical reaction using words or chemical formulas
reactant
a substance that undergoes a chemical change
product
a substance formed in a chemical change
word equation
shows the names of the chemical elements and compounds in a chemical reaction
skeleton equation
shows the chemical formulas in a chemical reaction
balanced equation
shows the reactants and products in the chemical equation with coefficients
diatomic elements
two of the same elements joined by a covalent bond (H2, N2, O2, F2, Cl2, Br2, I2)
polyatomic elements
many atoms of the same element joined by a covalent bond (S8, P4)
subscripts
indicate how many atoms of each element are present (in Al2Br3, 2 and 3 are the subscripts)
coefficients
indicate how many molecules are present (in 2S8, 2 is the coefficient)
how do u balance a chemical equation
number of atoms on the reactant side must equal number of atoms on product side. law of conservation of mass is reflected in balanced chemical equation. use coefficients in front of chemical formula
matter and energy react in __ and __ changes
physical and chemical
there is a transfer of energy between chemical reactions and the…
surroundings
energy
needed for everyday processes, transferred between system and surroundings. energy that leaves system enters surroundings, energy that enters system came from surroundings
activation energy
minimum amount of energy needed for reaction to happen
in chemical reactions, reactants must…
collide with enough energy to break bonds
energy changes occur with all…
chemical reactions
photosynthesis
process that captures sunlight to produce sugar molecules for plants
animals that eat plants can use energy stored in sugar through…
cellular respiration
exothermic reaction
chemical reaction in which there is net release of energy to surroundings. temperature increases as energy is released into surroundings
endothermic reaction
chemical reaction in which there is net absorption of energy from the surroundings. temperature decreases as energy is absorbed by system
cellular respiration equation
C6H12O6 + 6O2 = 6CO2 + 6H2O
energy-level diagrams
show energy changes in a reaction. in endothermic reaction, energy of product is greater than that of reactants. in exothermic reaction, energy of product is less that that of reactants.
synthesis reaction
chemical reaction in which 2 or more reactants combine to form single product. most are exothermic. A + B = AB
decomposition reaction
chemical reaction in which compound is broken down into elements or simpler compounds. most are endothermic. AB = A + B
single replacement reaction
chemical reaction in which an element and compound react to produce another element and another compound. A + BX = AX + B
double replacement reaction
chemical reaction in which solutions of 2 ionic compounds react to produce 2 new compounds. precipitate (ppt) is usually produced. metal replaces metal, non metal replaces non metal. AX + BY = AY + BX
combustion reaction
chemical reaction in which compound or element reacts with oxygen to produce an oxide of element. many produce heat and light. also refers to burning of hydrocarbons to produce CO2 and H2O
hydrocarbon
compound that consists of carbon and hydrogen. general equation for combustion of hydrocarbon is CxHy + O2 = CO2 + H2O. hydrocarbon combustions are exothermic.
incomplete combustion
occurs when low amounts of oxygen are available. produces carbon dioxide, water, carbon monoxide and soot
acid
compound that forms H+ ions when dissolved in water. chemical formula for acid has H in it
binary acid
consists of hydrogen and non-metal (HCl)
oxyacid
consists of hydrogen, oxygen and another element (H2CO3)
base
compound that forms OH- ions when dissolved in water. chemical formula for base has OH in it
acid-base indicators
used to identify acids and bases by changing colours
pH scale
used to measure pH. ranges from 0-14, if solution has pH if less than 7, it’s acidic. basic solutions have pH of greater than 7. neutral substances have pH of equal to 7.
neutralization reaction
chemical reaction in which acid reacts with base to form salt and water. it is type of double replacement reaction. (e.g. HCl + NaOH = H2O + NaCl)
hydrochloric acid (aqueous hydrogel chloride)
HCl(aq)
hydrofluoric acid (aqueous hydrogen fluoride)
HF(aq)
sulphuric acid (aqueous hydrogen sulfate)
H2SO4(aq)
nitric acid (aqueous hydrogen nitrate)
HNO3(aq)
carbonic acid (aqueous hydrogen carbonate)
H2CO3(aq)
acetic acid (aqueous hydrogen acetate, or ethanoic acid)
CH3COOH(aq)
lye, caustic sode (sodium hydroxide)
NaOH(aq)
Milk of Magnesia (magnesium hydroxide)
Mg(OH)2(aq)
lime water (calcium hydroxide)
Ca(OH)2(aq)
lone pair electrons
a pair of valence electrons that are not shared with another atom. Lone pairs are found in the outermost electron shell of atoms. found in Lewis structure.
bohr diagram
a diagram of an atom which includes all protons, neutrons, electron shells, and electrons
lewis diagram
a diagram that illustrates chemical bonding by showing only an atom’s valence electrons and its chemical symbol