C1 - Atomic Structure & The Periodic Table Flashcards
What is an atom?
The smallest particle of an element that can exist.
What is an element?
A substance that is made up of one type of atom only.
What is a compound?
A substance made from atoms of different elements chemically bonded together, in fixed proportion.
What is a mixture?
Two or more substances combined together but not held together by a chemical bond.
What is an isotope?
Form of an element with atoms that have the same number of protons but a different number of neutrons
What is relative atomic mass?
What is the equation for RAM?
The average mass of the atoms in an element.
(Mass 1 x % 1) + (mass 2 x % 2)
———————————————
100
What is the radius of an atom?
About 1x10⁻¹⁰ metres
How large is the nucleus compared to the atom?
Less than 1/10,000 of the atom’s radius
What is the overall charge of an atom? Why?
0 because the number of protons and electrons is always equal.
What is the relative charge and relative mass of a proton?
Charge: +1
Mass: 1
What is the relative charge and relative mass of a neutron?
Charge: 0
Mass: 1
What is the relative charge and relative mass of a electron?
Charge: -1
Mass: almost 0 (1/1836)
What does filtration do?
What is an example of filtration?
Separates insoluble solid from liquid
Sand and water
What does crystallisation do?
What is an example of crystallisation?
Separates soluble solid from liquid
Salt and water
What does simple distillation do?
What is an example of simple distillation?
Separates 2 liquids OR soluble solid from liquid when collecting both
Ethanol and water
What does fractional distillation do?
What is an example of fractional distillation?
Separates multiple liquids with different boiling points
Crude oil
Paper chromatography practical
- Draw a line with pencil near the bottom of the filter paper
- Add a spot of the ink to the line and place the paper in a beaker of solvent (e.g. water)
- The solvent used depends on what’s being tested. Some compounds dissolve well in water and sometimes other solvents like ethanol are needed.
- Place a lid on top of the container to stop the solvent from evaporating
- The solvent seeps up the paper and carries the ink with it
- When the solvent has nearly reached the top, take the paper out of the beaker and leave it to dry
- The end result is a pattern of spots called a chromatogram
What is the timeline of the history of the atom?
1800’s - Hard spheres (John Dalton)
1897 - JJ Thompson created the plum pudding model
1909 - Ernest Rutherford conducted the alpha particle scattering experiment
1911 - Ernest Rutherford created the nuclear model of the atom
1913 - Niels Bohr
1932 - James Chadwick discovered neutrons
What was the plum pudding model?
Who created the plum pudding model?
Atoms were spheres of positive charge with tiny negative electrons stuck in them
J. J. Thomson (in 1897)
What was the plum pudding model replaced with?
1911 - The nuclear model
- Most of the atom is empty space
- There is a concentrated mass in the middle - nucleus
- Atoms contain positively charged particles (protons) in the middle
What was the alpha scattering experiment?
- Positively charged alpha particles were fired at a thin sheet of gold foil
- Most went straight through but a few scattered
What was the nuclear model replaced with?
In which year?
1913 - The Bohr model
Electrons are in fixed shells around the nucleus.
What was the Bohr model replaced with?
The current atomic model
1932 - James Chadwick discovered neutrons and created a model closest to the current atomic model
What are the electron shell rules?
- electrons always occupy shells
- the lowest energy levels (closest to nucleus) are always filled first
- there is a limited number of elctrons allowed in each shell - 2,8,8
- most atoms don’t have full outer shells, which makes them likely to react to fill it
What is the timeline of the development of the periodic table?
1800’s - Elemnts were arranged by atomic weight
1864 - Newland’s theory: “law of octaves”
Every eighth element has similar
properties and reacts in a similar way.
1869 - Dmitri Mendeleev left gaps for element he predicted would be discovered
Now - Elements are arranged by increasing atomic number (mass)
How did Mendeleev arrange the elements?
Why did Mendeleev leave gaps in his periodic table?
By increasing atomic number (mass) instead of increasing atomic weight.
Mendeleev leave gaps in his periodic table because he correctly predicted some elements had not been discovered.
1) What does the group number of an element tell you?
2) What does the period an element is in tell you?
1) The number of electrons in the outer shell
2) The number of shells
What is group 1 on the periodic table?
&
What happens as you move down the group?
Alkali metals: metals that produce alkaline solution when they react with water.
They are reactive and soft metals.
reactivity increases, lower melting & boiling points, and higher relative atomic masses
What is group 7 on the periodic table called?
&
What happens as you move down the group?
Halogens: non-metals with coloured vapours
Become less reactive, higher melting & boiling points, and higher relative atomic masses
What is group 0 on the periodic table called?
&
What happens as you move down the group?
Noble gases: inert and colourless gases
The boiling points increase as you move down because there are more electrons in each atom (so there are greater intermolecular forces between them)
Evaporation
Crystallisation
Simple distillation
Fractional distillation
