Lets react Flashcards
Inside atoms
An atom consists of a heavy nucleus of protons and neutrons, surrounded by space containing moving electrons.
Protons, neutrons and electrons are called subatomic particles.
Protons
located in the nucleus, the mass compared to 1x electron is x1800. the electric charge is +1
Neautron
located in the nucleus. The mass compared to 1x electron is x1800. The electric charge is 0.
Electron
located in the shells around the nucleus. The mass compared to 1x electron is 1. electric charge is -1
Atoms are neutral
This means that the number of protons (+) is equal to the number of electrons (-).
Atomic number
The number of protons an atom has.
Mass number
The number of protons plus neutrons in the nucleus.
Sub-atomic particles
The number of protons plus neutrons in the nucleus. Electrons orbit/move around the nucleus in regions of space called shells.
Early Models of the Atom
Electrons are arranged in shells (energy levels). The levels closest to the nucleus are of less energy than those further away (think stability).
Electron Levels (Shells)
The Low energy electrons are closest to the nucleus. The first shell (1) is lowest in energy, 2nd level next and so on
Electron configuration
1st shell: 2 electrons maximum
2nd shell: 8 electrons maximum
3rd shell: 8 electrons maximum
4th shell: 2 electrons maximum
Electron movement through shells
Electrons can sometimes move to a new energy level / shell. An electron absorbs energy to “jump” to a higher energy, less stable level. When an electron falls to a lower energy, more stable level, energy is emitted as coloured light.
Flame Tests - purpose?
Provide evidence for the existence of energy levels .Used to identify a few metals.
Flame test colours
lithium goes red, sodium goes orange and copper goes teal.
Explain why the outer shell (valence shell) electrons are important
because it shows insight into the chemicals properties and determines its reactivity to form other chemical bonds.
ion
An ion is an atom or group of atoms that has an electrical charge, either positive or negative.
cation
is a positive ion that has lost and electron or more.
anion
is a negative ion that has gained an electron or more.
why do atoms form ions?
they make ions to create stability, which in tales a full outer shell.
which elements form cations
metals loses electrons to create cations
which elements form anions
non-metals gain electrons to create anions.
how do bonds form between ions
The opposite charges on the ions cause the ions to bond, or be held together, by electrostatic forces.
Law of Conservation of mass
The Law of conservation of mass states that matter can neither be created or destroyed.
describe how to do an experiment to show the Law of conservation of mass
The total mass of the reactants equals the total mass of all the products.
indications a chemical reaction has occured
change in colour, temp change, bubbles, a solid appears or disappears, and odour is produced, and a flame or light becomes present
What are the reactants of a chemical reaction?
The reactants are the starting substances that undergo change during the reaction to form new products.
What are the products of a chemical reaction?
The products are the substances that are formed as a result of the reaction between the reactants.
What is a physical change?
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition, and can be reversed
What is a chemical change?
is a change of materials into another, new materials with different properties and one or more than one new substances are formed, and cannot be reversed
Explain the meaning of ‘rate of a chemical reaction’?
The rate of a chemical reaction refers to the speed at which reactants are converted into products over a given period of time.
List the factors that can increase the rate of a chemical reaction
Temperature
Surface area
Concentration of reactants
Use of a catalyst/enzyme
How does temperature affect the rate of reaction?
As the temp is increased so is the rate of reaction, this is because at a higher temp the particles have more kinetic energy there for they are more likely to collide.
How does an increased concentration affect the rate of reaction?
at a higher concentration, there are more particles in the same amount of space meaning the particles are more likely to collide.
How does an surface area affect the rate of reaction?
As we increase the surface area, we increase the rate of reaction. If the solid is split into several pieces, the surface area increases. this means more area for the reactant to collide with.
How does an enzyme/catalyst affect the rate of reaction?
catalyst are chemical that speeds up a chemical reaction. A catalyst provides a surface for the reaction to take place on and hence increases the frequency of collisions.
Explain the function of a catalyst.
catalyst are chemical that speeds up a chemical reaction. The benefits are; Products can be made more quickly, saving time and money, they reduce the need for high temperatures, saving fuel and reducing pollution.
