Test 2 Flashcards
What is always formed in a chemical reaction?
A new substance
What are four sighns that a chemical reaction is occuring?
A colour change
A gas being produced (effervescence)
A solid being produced (precipitation)
An energy change
What are the differences between an exothermic and endothermic reaction?
- Exothermic reactions RELEASE HEAT, causing the temperature of surroundings to rise.
-Endo thermic reactions ABSORBS HEAT, causing the surrounding temperature to cool
Explain how changing the temperature, concentration and particle size of the reactant can change the rate of reaction
In order to increase the rate of reaction you
can:
Increase temperature
Increase concentration
Increase surface area
-Increasing the concentration means there are more reactant particle in a given space
-With an increase in temperature, there is an increase in the number of collisions.
-By decreasing the particle size of a reactant, we are increasing its surface area
the rate of reaction can change because th
what is the effect of a catalyst on a chemical reation ?
INCREASES THE RATE OF CHEMICAL REACTION but it is not used up (remains chemically unchanged at the end)
Where can a enzyme and a catalyic converter be found and why are they important ?
Catalytic converter:
-found attached to the exaust pipe of a veicle
-Important because it converts the chemicals thats are bad for the environment into less toxic pollutants
Enzymes:
-can be found in living organisms stomach e.g. intestines and saliva
-important because they are a catalyst snd speed up chemical reactions and are not used up in the proccess.
what is the importance of making an experiment a fair test?
how can this be done?
-If the test is not done fairly, then it will DECREASE THE EFFECTIVENESS AND RELIABLITY OF THE EXPERIMENT because the results will be wrong
-can be done by measuing things consistantly, getting an average score and repeating the experiment multiple times
what is the importance of making an experiment a fair test?
how can this be done?
-If the test is not done fairly, then it will DECREASE THE EFFECTIVENESS AND RELIABLITY OF THE EXPERIMENT because the results will be wrong
-can be done by measuing things consistantly, getting an average score and repeating the experiment multiple times
What is an atom ?
what is a molecule ?
what is a compound ?
Atom : Atom are the bulding blocks of everything and is the smallest particle of an element
MOLECULE: A molecule is made up of two or more atoms that are NOT chemically bonded together
COMPOUND: a compound is made up of two or more different types of atom chemially bonded together
What does covalent bonding exist between?
Covalent bonding exists between NON-METAL ELEMENTS
What is a covalent bond?
It is an ectrostatic attraction between both nuclei in the bond and the shared pair(s) of electrons
why do non-metal atoms join covalently?
in order to acheive a full shell of electrons
What is meant by a lone pair of electrons?
a lone pair is a pair of electrons which are in the outer shell if a covalently bonded atom but are not involved in the bonding.
e.g. the oxygen in a water molecule has 2 lone pairs
what are the differences between covalent molecules and covalent networks?
covalent molecules are just one bond, and cant expand
Covalent networks are a huge network of and element and can expand
what are three types of covalent network elements?
Boron carbon and silicon
What are 2 covalent network compounds?
Carbon Sulfide
Silicon Dioxide
What does an ionic bond exist between?
between metals and non-metals
what is an ion?
an atom or molecule that has an electric charge because it has lost or gained one or more electrons
How does the process of electron transfer lead to an ionic bond
Explain the charge on metals as they become ions
Metal atoms lose electrons from their outer shell when they form ions: the ions are positive, because they have more protons than electrons.