Atomic Structure Flashcards
How many Elements are there estimated to be in the Periodic Table
Around 100
Define an element?
A substance that is made up of only one type of atom e.g. magnesium (Mg) helium (He) oxygen (O2)
Define a Compound
Compounds contain two or more different elements chemically combined in a fixed proportion
True or False: Compounds usually have identical properties to the elements that they are made from
False; they are usually totally different
How can the elements in a compound be separated?
By using a chemical reaction.
True or False: In a specific compound, the number of atoms of each element is fixed
True
How many atoms of oxygen are there In Al(OH)3
3 Atoms
What are the 4 techniques of physical separation
Filtration, Crystallisation, Distillation and Chromatography
What are Physical Separation Techniques used for?
Separating Mixtures
How do you Separate Elements in a compound
Using a Chemical Reaction
What technique is used to separate a insoluble solid from a liquid?
Filtration
True or False: Filtration is used to separate a soluble solid from a liquid?
False; Crystallisation is used
What happens when a solute (e.g. salt) dissolves in a solvent (e.g.water)?
The bonds holding the solute together break and mix with the particles in the solvent forming a solution.
Define a solution?
A mixture of a solute and a solvent which doesn’t separate out.
What does the term saturated mean?
No additional solvent will dissolve at that temperature.
Define an Isotope?
Isotopes are atoms of an element with different numbers of neutrons.
True or false: Atoms have an overall amount of charge
False; atoms do not have any charge. The number of electrons (negatively charged) equals the number of protons (positively charged).
Which parts of an atom are charged
Protons and Electrons
Define Ions
Ions are atoms that have an overall charge. They have gained or lost electrons.
How do you calculate the relative atomic mass of an elements isotopes?
Relative atomic mass = The average of the mass numbers for the different isotopes weighted for the abundance of each isotope.
(M1 x abundance ) + (M2 x abundance) / 100
What is the maximum number of electrons that can be held in each of the 4 energy levels (electron shells)
First level - 2
Second level -8
Third level - 8
Fourth level -18
Group 1 metals have how many electrons in their outer energy level?
Answer: One - The number of electrons in the outer shell tells us the group number of the element in the periodic table.
Elements with full outer shells of electrons are found in which group of the periodic table?
Group 0 - Noble gases
What do all of the elements in a group of the periodic table have in common?
- They have the same number of electrons in their outer shell
- They react in the same ways
How are elements arranged in the modern periodic table?
By atomic number, that is the number of protons.
What did Döbereiner call similar elements that appeared in three
Triads
What does Newlands’ Law of Octaves state?
That If you arrange the elements in atomic weight, every eighth element reacts in a similar way.
Who developed the first modern Periodic Table?
Dmitri Mendeleev
Name 2 differences in the modern periodic table compared to Mendeleev’s original Table.
- The elements were arranged in order of atomic mass, whereas now it is ordered by atomic number
- Group 0 (The Noble Gases) was discovered
Why are all of the noble gases unreactive?
They have a full outer shell, stabilising the atom.
What happens to the boiling points of the noble gases as they go down the group?
The boiling points increase.
What happens to the electron structure when metals react?
It loses electrons to achieve a full outer shell.
What do all group 1 metals have in common?
They all have 1 electron in their outer shell (and they’re soft).
Group 1 metals become more/ less reactive as you go down the group?
More reactive
What happens to the outer electron as the elements move down group 1?
It is less attracted to the nucleus and easier to lose. The outer electron is shielded from the nucleus by the internal energy levels.
Define a mixture?
A mixture contains 2 or more different substances where the substances are not chemically combined.
