Unit 1 Chemical Changes + Structure Flashcards
revision for test
what is an element?
an element is a substance that consists of only one type of atom
True or False everything in the world is made up of just over 97 elements
False everything in the world is made up of just over 100 elements
what is the periodic table?
The periodic table is the arrangement of all known elements
What are most elements?
solids
true or false only 2 elements in the periodic table are liquids
true
true or false many of the non metal elements are solids
false most of them are gases
what are the vertical columns of the periodic table called?
groups
What are the horizontal rows on the periodic table called?
periods
what are the groups numbered as?
1-7 but the last group is either 8/0
what do all the different groups have?
They all have different chemical properties e.g.** group 1 is very reactive** with sodium and potassium having very violent reactions
true or false an element only contains 1 type of atom
true
what is a chemical symbol?
A chemical symbol is a short hand way of representing an element. Each element had its own chemical symbol.
what does a modern chemical symbol look like?
They consist of one or two letters. The first one is a capital letter but the second one (if it has one) is lower case. e.g H - Hydrogen or Fe - Iron
how many electrons does group 1 have on its outermost shell
the group 1 elements all have 1 outer electron. its teh sma efor all of the groups
true or false group 1 is very reactive
true
true or false group 7 is not very reactive
false group 7 is very reactive
true or false group 2 is normal reactive
true
true or false group 8/0 is the most reactive
false group 8/0 is not reactive
what is a mixture?
when two or more elemnts are jumbled together but dont chemically join
what is a compound?
In a compound, two or more elements are chemically joined. They are held by very strong bonds and cannot be easily seperated back into their elements.
what is a solution?
a mixture formed when a solute dissolves in a solvent.
what is a solute?
the substance that dissolves in the solvent
what is a solvent?
the substance which other substances dissolve in.
what does it mean if a substance is soluble?
a substance that can dissolve
what is a dilute solution
a small amount solutedissolved in solvent
what is a saturated solution?
when the maximum amount of solute has been dissolved in the solvent.
what is a state symbol
the state symbol is a superscript in brackets following the name of the substance
whats the state symbol for solids?
(s)
whats the state symbol for liquids?
(l)
whats the state symbol for gas?
(g)
what the state symbol for a solute dissolved in water?
(aq)
what always happens in a chemical reaction?
A new substance is produced. There will also always be signs for a new substance being produced.
How many elements are in an -ide compound?
2 elements
true or false compounds that contain 2 elements + oxygen end in xyz
false they end in -ite or -ate
what would iron sulphide be made of?
iron+ sulphate
what would zinc carbonate be made of?
zinc+carbon+oxygen
what would alumininum sulphite be made of?
aluminium+sulphur+oxygen
true or false hydroxide means made of hydrogen and oxygen
true e.g sodium hydroxide = sodium+hydrogen+oxygen
what is a rate of a chemical reaction?
how fast the reaction happens
what must happen for a chemical reaction?
the particles must collide with energy and the correct allignment
what does it mean if the particle size decreases
the rate of reaction increases as there is more surface area for particles to collide e.g calcium carbonate powder reacts faster than calcium carbonate lumps
what does it mean if the particle size increases
the rate of reaction decreases as there is less surface area for particles to collide
what happens to the reaction rate as temperature is increased?
when the temperature is increased the particles move faster - there are more collisions => faster reaction rate
what is an exothermic reaction?
an exothermic reation is a reaction that releases enegergy in the form of heat.
what is an endothermic reaction
an endothermic reaction absorbs (takes in energy) .
what are some of the signs of a chemical reaction?
- colour change
- gas given off (smell or fizzing)
- changing temperature
what happens to the rate of reaction when there is a lower concentration?
The reaction rate is slower as there are less particles => less collisions
what happens to the reaction rate when there is a higher concentration?
The reaction rate is quicker as there are more particles => more collisions
What effects the rate of reaction?
- temperature
- particle size
- concentration
- catalyst
what are the two types of catalyst?
hetrogenous and homogenous
what is a hetrogenous catalyst?
a hetrogenous catalyst is one which has a different physical state to the reactants e.g solids and liquids etc
what is a homogenous catalyst?
a homogenous catalyst is aone which has the same physical state to the reactants
what is a catalyst
Catalysts are substances which speed up a chemical reaction without being used up in the process
what is an enzyme?
Enzymes are biological catalysts i.e they exist in living things and reaction happen in them
do all enzymes work?
some do and some don’t
True or False enzymes are highly specific to which they catalyse
true a suitable enzyme must be used for an appropriate reaction
If there is an increase in particle size
reaction rate decreases
if there is a decrease in particle size
reaction rate increases
increase in concentration
reaction rate increases
decrease in concentration
reaction rate decreases
increase in temperature
reaction rate increase
decrease in temperature
decrease in reaction rate
add a catalyst
reaction rate increases
What can the progress of a chemical reation be followed by?
measuring the change in
-mass
-volume
-concentration
