Unit 4: Reactions

chemical reaction

rearrangement of existing atoms with no loss or gain of atoms

law of conservation of mass

states that the matter isn’t created or destroyed, it only changes form in a chemical reaction….this means that the total amount of atoms going in or out have to be equal 

how many diatomic elements are there?

7

diatomic elements

exist in nature as two bonded atoms of the same element

what are the diatomic elements 

HOFBrINCl

What are the five changes that serve as evidence of a chemical reaction?

temp, color, odor, PPT, bubbles, and light

temp change 

energy release or absorption 

color change

indicates the formation of new products with different chemical properties

odor change

the production of gas may result in a noticeable change in odor

formation of preciapiae (PPT)

insoluble solid forms

formation of bubbles

gas production

Splint test identifies hydrogen what does this mean 

squeaky “pop” sound - burning lit 

splint test identifies oxygen what does this mean

splint reignites or burns back into flame - indicates the gas is an oxidizer and supports combustion - glowing splint 

splint test identifies carbon dioxide what does this mean

splint’s flame is extinguished - indicates the gas does not support combustion

What will happen to ionic compounds when they placed in water

either sink or dissolve depending on their solubility. Soluble ionic compounds dissolve and insoluble ionic compounds will sink 

molecule

group of two or more atoms held together by chemical bonds - most commonly covalent bonds 

ionic bond

transfer of electrons from one atom to another, occurs when a metal and non-metal atom.results in neutral ionic compound 

covalent bonds

formed by sharing of one or more pairs of electrons between two atoms, often to fill outermost shells, between non-metal atoms 

polyatomic ions

group of two or more atoms held together by covalent bonds that act as single unit with an overall positive or negative charge 

reactants

the starting substances in a chemical reaction that are used to create new substances

products

any substance that is formed as a result of chemical reaction

coefficients

number in front of a symbol - tells you how many molecules there are

double replacement reaction

two compounds as reactants and products (one may form a solid precipitate)

single replacement reaction

you start with one compound and one element react to form a new compound and a new single element 

insoluble 

substance cannot dissolve in a specific solvent, such as water to form a solution 

Compete ionic equation

shows all soluble ionic compounds as they appear with charge, subscription, state and are like spilt and breakdown

net ionic equation

shows only the species that participate in a reaction, excluding spectator ions. Focuses on formation of precipitate (gas or water or solid)

spectator ion

don’t form anything we cannot count them in a reaction

(s)

solid: state of matter that has a definite shape and volume

(g)

gas:state of matter that has neither a fixed shape nor fixed volume

(l)

liquid: state of matter that has a definite volume, but not fixed shape 

(aq)

aqueous: substance is dissolved in water, forming a solution where water is the solvent 

combustion reaction

usually reaction between a hydrocarbon and oxygen to yield carbon dioxide, water and heat. Chemical reaction between a fuel and oxidant 

synthesis reaction 

two or more simple substances, called reactants combine to form a single, more complex product

Decomposition reaction

single compound breaks down into two or more simpler substances or elements

precipitate

form an insoluble solid. You can identify by change in solution ALWAYs a solid that forms usually when two solutions or liquids are mixed to create insoluble compound 

soluble

all reactants and products remain disssolved in solution

solvent 

substances, typically liquid that dissolves a solute to form a solution 

yields

the amount of product obtained from a chemical reaction

molecular equation

shows each of the substances in the reaction as compounds with physical states written next to the chemical formulas 

What are always soluble (aq) 

nitrates, all group 1, and all ammonium