Topic 1: Let's React Flashcards
Define Atoms
All of the materials around us are made up of tiny building block
Define Element
When a substance is made up of one type of atom
Proton: Location, Mass, Electrical Charge
nucleus, X1800, +1 charge
Electron: Location, Mass, Electrical Charge
shell around the nuclues, X1800, no charge
Neutron: Location, Mass, Electrical Charge
Shell around the nucleus, 1, -1 charge
How to find no. of neutrons?
Mass number - atomic number
Rule the maximum number of electrons each shell can hold.
2n^2, where n = the shell number
Electronic Configuration
2,8,8,2
What do the periods show on the periodic table?
The number of shells that contain electrons. It is numbered 1-7.
What do the groups show on the periodic table?
The number of electrons in the outer (valence) shell. For groups 13-18, subtract 10.
What does the atomic number of an element tell us?
The amount of electrons and protons in an element.
What does the mass number of an element tell us?
How many protons + neutrons.
What is the ground state
Electrons in the lowest energy shells
What does heating an element cause it to do?
- causes an electron to absorb energy and jump to a higher energy level.
- the electron is excited and unstable and quickly returns to a lower energy level
- releases a fixed amount of energy in the form of coloured light!!
- visible light can be emitted when electrons return to a lower energy level
What ion causes the flame colour to differ? Give evidence
It is the metal cation causing the flame colour as we tested compounds where different metal cations bonded with the same ion.
List 3 limitations of flame tests
- Different metals may produce similar flame colours
- Most metal ions are not excited by the flame of a bunsen burner as it is not hot enough
- Low accuracy and the tests are purely qualitative.
Applications of flame tests
- Fireworks
- Electric Street Signs
- Street Lights (Sodium Chloride)
What is an excited state?
any energy state higher than the ground state. It is less stable and tends to return to the ground state by releasing energy in the form of light.
What is a photon?
Coloured light energy
What is an ion?
is an atom or a group of atoms that has an electrical charge, either positive or negative
What is a cation?
An atom that loses electrons and therefore has more protons than electrons, having a positive overall charge
What is an anion?
An atom that gains electrons, having more electrons than protons and so has a negative overall charge.
Example of ion on calcium
Calcium (2,8,8,2) loses 2 electrons to from Ca^2+ (2,8,8) which is the same electronic configuration as Argon (2,8,8) which is Calciums nearest Noble gas.
What determines how an atom behaves?
The number of electrons it has surrounding the nucleus.
What is special about noble gases
They are the least reactive elements, already having full outer shells, therefore they don’t need to lose or gain electrons.
What happens to metal atoms to gain a full outer shell?
They lose electrons
What happens to non-metal atoms to gain a full outer shell?
They gain electrons
Law of Conservation of Mass
States that during a chemical reaction, matter cannot be created or destroyed. All the atoms present at the start of the reaction are present at the end.
Characteristics of a chemical reaction
the chemical bonds holding the atoms together break and form new substabnces. Chemical change is difficult, if not impossible to reverse
Examples of chemical change
Burning toast, cooking an egg, burning wood in fire are all examples of a chemical change.
What does COBALT stand for?
C olour Change
O dour Change
B ubbles appear
A ppearance or disappearance of a solid
L ight or sound produced
T emperature change
What happens during a chemical reaction?
The bonds in the reactants are broken the atoms are re-arranged and new bonds form to make products.
Reactants
Substance you have at the beginning
Products
When the reaction is complete
Why are symbols used in chemical reactions?
- to show the state of the reactants
- to show the state of the products
- reaction conditions
(s)
solid
(l)
liquid
(g)
gas
(aq)
aqueos
Examples of slowing down reactions
fruit going brown, spoiling of food, rusting
What is the collision theory?
The more collisions between particles ina. given time, the faster the reaction
What does a collision need in order for it to be successful?
the molecules must collide with enough energy and the particles must have the correct orientation
What happens if particles collide with lower energy?
If they collide with less energy than the minimum required, they will bounce off each other.
The rate of measure is…
how fast the products are made or reactants are used up.
What happens to rate of reaction overtime?
The concentration of reactants decreases, reducing the frequency of collisions between particles and so the reaction slows down.
Why does increased temperature increase the rate of reaction?
The particles have more energy, meaning they are more faster and are more likely to collide with other particles. When the particles collide, they do so with more energy, and so the number of successful collisions increases.
What happens to the rate of reaction in a cold mixture?
The particles move more slowly, collisions are less frequent and have less energy so there are fewer successful collisions.
Why does increased concentration increase the rate of reaction?
- At a higher concentration there are more particles within a given volume. This means that the particles are more likely to collide and therefore more likely to react.
Why does increased surface temperature increase the rate of reaction?
There is an increased area for the reactant particles to collide with. The smaller the pieces, the larger the surface area, meaning more collisions and a greater chance of reaction
Why does the use of a catalyst increase rate of reaction?
It provides a surface for the chemical reaction to take place on and hence increases the frequency of collisions. It also provides a different pathway for the reaction with lower energy required.
Why are catalysts so important for the industry?
- Products can be made more quickly, saving time and money
- Reduce the need for higher temperatures, saving fuel and reducing pollution
- Are not used up in reactions, so they can be recovered chemically unchanged. This means they can be used again and again.
