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Where are the protons and neutrons located?
Protons and neutrons are located in the centre of the atom and they have a radius of around
1 × 10^-14
They have a positive charge because of the protons and the whole mass of the atom is concentrated in the nucleus
Where do the electrons orbit?
The electrons move around the nucleus and electron shells. They are negatively charged and tiny but they cover lots of space. the volume of their orbits determine the size of the atom. And the electrons are so small that they virtually have no mass
What is the charge of a proton and relative mass of a proton
A proton has a plus one charge and a relative mass of one
What is the relative mass and charge of a neutron?
A neutron has a relative mass of one and a charge of zero
What is the relative mass and charge of an electron?
The relative mass is so small that it’s often taken a zero and their Is -1
What is the overall charge of a atom?
Atoms are neutral because they have the same number of protons as electrons the charge on the electrons is the same size as the charge on the protons but the opposite to the charge is cancelled out
What is an atomic number?
Atomic number tells you how many protons there are
What is the mass number?
The mass number tells you the total number of protons and neutrons in the atomU
What is an isotope?
Isotopes are different forms of the same element which have the same number of protons but a different number of neutrons so isotopes have the same atomic number of different mass numbers
A very popular example of a pair of tote of carbon 12 and carbon 13
Why is relative atomic mass used?
Because many elements can exist as a number of different isotopes relative atomic mass(Ar) Is used instead of mass number one referring to the element as a whole. This is an average mass taking into account of different masses and abundances of the isotopes that take up the element
What is the formula to find out the relative atomic mass?
Example of how relative atomic mass formula is used in a question
What are compounds?
Compounds are substances formed from two or more elements that are chemically combined in fixed proportions
Compound are formed and separated using chemical reactions. Chemical reactions always involve the formation of one or more new substances and often involve an energy change
Making bones involves atoms giving away, taking or sharing electrons. The electrons are involved, not the nuclear of the atoms
What is ionic bonding?
Ionic bonding is when a metal and a non-metal react together. This compound would consist of ions. The metal atoms lose electrons to form positive ions and the non-metal atoms gain electrons to form negative ions. The opposite charges of the ions mean that they’re strongly attached to each other.
What is covalent bonding?
Covalent bonding is when two nonmetals react to form a compound. This consists of molecules. Each atom shares an electron with another atom.
What is a mixture?
A mixture consists of two or more elements or compounds not chemically combined together. The chemical properties of each substance in the mixture are unchanged.
Mixtures can be separated by filtration crystallisation, simple distillation, fractional distillation and chromatography. These are physical processes so they do not involve chemical reactions and no new substances are made.
Crude oil is an example of a mixture of different length hydrocarbon molecules
Explain the method of paper chromatography
Chromatography can be used as a technique to separate different dyes and inks
First, you need to draw a line near the bottom of the sheet of the filter paper about one cm from the bottom Use a pencil to do this because the pencil marks are insoluble and won’t dissolve in the solvent
Add the spot of the ink to the line and place the sheet in a beaker of solvent
The solvent depends on what is being tested some compound dissolving water but some other solvent like Ethanol or HCL
You have to make sure that the ink is not touching the solvent. You don’t want it to dissolve into it.
Place a lid on the top of the container to stop the solvent from evaporating
The water will travel up the filter paper carrying the ink with each different dye in Körper. The ink has different solubilities so they will travel different distances up the filter paper.
If any of the guys in the ink are insoluble in the solvent you’ve used they’ll stay on the baseline when the solvent has nearly reached the top of the paper take the paper out and leave it to dry.
The end result is a pattern of sport called chromatogram
What is filtration?
Filtration can be used if your product is an insoluble solid that needs to be separated from a liquid reaction mixture
It can be used in purification as well. For an example of solid impurities in the reaction mixture can be separated using filtration
What are the two methods that soluble solids are removed from solutions?
Evaporation and crystallisation
Explain Evaporation
The solution into an evaporating dish and slowly heat the solution. The solvent will evaporate and the solution will get more concentrated. Eventually, crystals will start to form keep heating evaporating dish until all you have left is dry crystals.
Explain crystallisation
For the solution into an protein dish and Gently heat the solution some of the solvent all of evaporate and the solution will get more concentrated once some of the solvent has evaporated or once you start to see crystals form remove the dish from the heat and leave the solution to call the sort should start to form crystals as it becomes soluble in the cold highly concentrated solution to the crystals out of the solution and leave them in a warm place to dry. You could also use a drying oven or a desiccator.
Explain simple Distillation
Simple distillation is used for separating out a liquid from a solution
First the solution is heated. The part of the solution that has the lowest boiling point of evaporates first. The vape part is then called and condensed as it runs down the condenser, This is then collected
Simple distillation can be used to get pure water from seawater as the water evaporates you are left with the salt in the flask
Disadvantage of simple distillation is that you can only use it separate things with different boiling points if the temperature goes higher than the boiling point of the substance with the higher boiling point they will mix again
What is fractional distillation and what is it used for?
If you’ve got a mixture of liquids with similar boiling points, you should use fractional distillation. An example of fractional distillation is used is when crude oil is separated out
First, you would put your mixture in a flask and stick A fractionating column on top These have little glass rods in it. Then you heat it. The different liquid will have different boiling points- so they will have evaporate at different temperatures. The liquid with the lowest boiling point of evaporates first when the temperature on the thermometer matches the boiling point of its liquid, it will reach the top of the column. Liquids Higher boiling points also starts to operate but the column is cooler to top so they will only get part the way up before condensing and running back down towards the flask when the first liquid has been collected. You raise a temperature until the next one reaches the top
What was the First development of the model of the atom
At the start of the 19th century, John Dalton described the atoms as solid Spheres, And said that different spheres made up different elements. And that they could not be divided
What was the next development in the model of the atom?
In 1897 JJ Thompson Concluded from his experiments that atoms werent Solid spheres. His measurements of charge and mass showed that atoms must contain even smaller negatively charged particles-Electrons.
His theory was known as the plum pudding model.The plum pudding model shows the atoms as a ball of positive charge with electrons stuck in it
What did JJ Thompson discover?
He discovered electrons and the plum pudding model
What was the next development of the model of the atom?
In 1909 Ernest Rutherford Conducted the alpha particle scattering experiment
They discovered that most of the atom is empty space .They discovered that the mass of an atom was concentrated at the centre and the nucleus was charged
His new model was called the nuclear model of the atom
What was the alpha particle scattering experiment?
They fired positively charged alpha particles at an extremely thin sheet of gold. From the plum pudding model, they were expecting the particles to pass straight through the sheet ought to be slightly deflected at most.
From the plum pudding model, they were expecting the particles to pass straight through the sheet ought to be slightly deflected at most. This was because the positive charge for each atom was thought to be very spread out through the pudding of the atom. Whilst most of the particles did go straight through the gold sheet somewhere deflected more than expected and a small number or deflected backwards so the plum pudding model could not be right
He then came up with an idea that there’s a tiny positively charged nucleus at the centre where most of the mass is concentrated. And a cloud of negative electrons surrounding this nucleus. So most of the atom was empty space. When the Alpha particles came near the concentrated positive charge of the nucleus, they were deflected.
What did Neil Bohr Discover
Scientists realise that the electrons in a cloud around the nucleus of an atom would be attracted to the nucleus causing the atom to collapse. So Neil bohr’s Nuclear model of the atom suggested that all the electrons were contained in shells. He proposed that the electrons orbit the nucleus and fixed shells and aren’t anywhere in between. Each shell is a fixed distance from the nucleus
What happened next in the development of the model of the atom?
Latest experiments prove that positive charge of any nucleus could be subdivided into whole numbers of small particles, each particles having the same amount of positive Charge(Protons)
What did James Chadwick discover?
He discovered neutrons
Before the discovery of protons, neutrons and electrons, how were the elements in the periodic table ordered?
John Newlands Arranged the elements in Atomic weights
He realised that similar properties occurred every eighth element so he came up with the law of
How did Dimitri Mendeleev overcome some of the problems in the early periodic table?
In 1869 Dimitri Mendeleev put the elements mainly in order of atomic Mass
Why did Dimitri Mendel leave leave gaps in the periodic table?
Gaps were left in the table to make sure that elements with similar properties stayed in the same groups. Some of these gaps indicated the existence of undiscovered elements and allowed mentally to predict what their properties might be.
When they were found and they fitted the pattern it helped Mendeleev’s Ideas
How are elements in the periodic table arranged?
Elements in the periodic table are arranged in increasing atomic number and so that elements with similar properties are in columns known as groups. The table is called a periodic table because similar properties occur at regular intervals.
What are groups?
Elements with similar properties from column and these vertical columns are called groups. Elements in the same group in the periodic table had the same number of electrons in the cell and this gives them similar chemical properties. The group number tells you how many electrons are in the shell for an example group one elements have one electron in the outer shell.
How do groups also allow you to predict the properties of elements?
If you have a properties of one element, you can predict the properties of other elements in that group for an example group one elements All react very similar way. You can also make predictions about trends in reactivity for example one elements react more vigourously as you go down the group and group 7 reactivity decreases as you go down the group
How does the electronic structure of atoms affect how they will react?
Atoms react to form full outer shells. They do this by losing, Gaining or sharing electrons. Metals towards the left of the periodic table don’t have many electrons to remove and metals towards the bottom of the periodic table have electrons which are a long way from the nucleus so feel a weaker attraction. Both these affects me not much energy is needed to remove the electrons. So it’s feasible for the elements to react to form positive ions with a full outer shell
How does electronic structure of atoms that are nonmetals affect how they react?
Forming positive ions for metals is much more difficult. This is because they are either to the right of the periodic table-Where they have lots of electrons to remove to get a full out of shell, Or where they’re electrons are close to the nucleus so they Feel a Strong attraction
So it is far more easier for them to either share or gain electrons to get full out of shells
What are the properties of metals?
Metals have metallic bonding So they are:
Strong but can be bent or hammered into different shapes
The great at conducting heat and electricity
They have high boiling and melting points
What are properties of nonmetals?
Nonmetals don’t have metallic bonding so they don’t tend to have the same properties as metals. They are dull looking, They are brittle And aren’t always solid at room temperature they have a lower density and don’t generally conduct electricity
What are the properties of Transition metals and where can they be found?
Transition metals are in the centre of the Periodic table between group 2 and group 3
Transition metals are good conductors of heat and electricity they are very dense, strong and shiny
Transition Metals can have more than one ion for an example copper formed Cu^+ and Cu^ 2+
Transition metals are often coloured and so compounds that contain them are colourful for an example potassium Manganate Is Purple
Transition metals are also often used as catalysts for an example nickel based catalyst is used in the hydrogenation of Alkenes
What are group one elements called?
Alkali metals
What are group 2 elements called?
Alkaline metals
What are the group 7 elements called?
Halogens
What are the group0/8 Elements called
The noble gases
What are the group 1 elements and what are their properties?
Group 1 elements are called alkali metals.They are: Lithium, Sodium, Potassium, Rubidium, caesium And Francium
They have one electron in their outer shell so they are very reactive
They are all soft and have low density
As you go down the group, they become increasingly reactive as the outer electron is more easily lost as the attraction between the nucleus and the electron decreases because the electron is further away from the nucleus the further down you go in the group
They have low melting and boiling points
Higher relative atomic mass
They all react with oxygen to create an oxide
They all react with chlorine for a white precipitate
What kind of ions do group one elements form?
1+ ions
What is group one elements reaction with water?
When group one elements are put in water, they react vigourously to produce hydrogen gas and metal hydroxides-Compounds that dissolve in the water to produce alkaline solutions
The more reactive and alkali metal is the more violent reaction is
The amount of energy given out by the reaction increases down the group. The reaction with potassium releases enough energy to ignite hydrogen.
What is the group one element reaction with chlorine?
Group one metals react vigorously when heated in chlorine gas form white metal Chloride salts
Great one element reaction with oxygen
They form a metal oxide different types of oxides will form depending on the group one metal
What are the properties of the halogens- Group 7 elements
Similar reactions as they all have seven electrons in their outer shell
They are nonmetals and exist as molecules made of pairs of atoms
They react with metals to form ionic compounds in which the halide ion carries a -1 charge
They react with nonmetals to form covalent bonds where there is a shared pair of electrons
As you go down the group reactive molecular mass melting point and boiling point or increase
Reactivity decreases as you go down the group
What are the halogens?
Fluorine-Is a very reactive poisonous yellow gas
Chlorine- is a fairly reactive poisonous dense green gas
Bromine-A dense poisonous red brown volatile liquid
Iodine Either a dark grey crystalline solid or a purple vapour
Why do the group 7 halogens become less reactive as you go down?
It’s hard to gain an extra electron because the outer shell is further away from the nucleus
What is the compound called when halogens react with nonmetals?
Simple molecular structures
What kind of ionic bonds do halogens form with metals?
1- ions called halides
What happens When a halogen is more reactive than another
A displacement reaction will occur for an example chlorine can displace bromine and iodine from an aqueous solution of its salt because it is more reactive
Elements closer to the top of the group 7 elements are the most reactive
What are the group 0 elements?
Group 0 elements are called the noble gases. They are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons. The gases have eight electrons on their outer shelf except for helium, which has only two
What are properties of group 0 elements?
Because they have a full outer shell, they are unreactive- inert
they exist as monatomic gases-Single atoms not bonded to each other
They are colourless gases at room temperature
And they’re not flammable
What is the pattern of the boiling points?
They increase as you move down the group along with increasing relative atomic mass
The increase in boiling point is due to an increase in the number of electrons in the atom leading to greater intermolecular forces between them which needs to be overcome.
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