3 Atomic structure and the periodic table Flashcards
What is the aufbau principle?
1s(2) 2s(2) 2p(6) 3s(2) 3p(6) 4s(2) 3d(10) 4p(6)
What is the first ionisation energy?
The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions
How do you write noble gas configuration?
You write the noble gas in square brackets then everything after that electron configuration afterwards
What are the anomalies in the electron configuration?
Chromium
Copper
(Both begin with C)
What is the electron configuration of copper? Why is it different?
[Ar] 4s(1) 3d(10)
It is more stable to have one full shell and one half full shell
What is the electron configuration for chromium and why is it different?
[Ar] 4s(1) 3d(5)
It is more stable to have two half shells
What do you have to write before the electron configuration of ions?
The symbol and the charge
What orbital must you remove electrons from first when writing the electron configuration for any ion?
4s
Describe Thompson’s plum pudding model of the atom
Negative electrons embedded in a sphere of positive charge
What was the experiment performed by Rutherford and his colleagues which led to the proposal of the nuclear atom?
They directed abeam out alpha particles at a thin metal foil
What did Rutherford observe that led to his proposal of atoms are mostly empty space with most of them are centred in a very small and nucleus?
Most alpha past pools pass straight through detected on the other side.. Somewhere deflected
It is the ratio of the diameter of the nucleus to the diameter of the atom?
1:10000
What was the experiment that Bohr studied that led to the concept of quantum shells?
A gas is heated or an electrical charge is passed through it. It gives out light which can be passed through the prism or diffraction grating that splits up to form spectrum
What is the series of lines produced by Bohrs experiment called?
Find spectrum or emission spectrum which is made up of a series of separate lines or bands
Explain the observations in Bohr’s experiment in terms of electrons and energy levels
Electrons are arranged in a shell around the positive nucleus. As you move away from the centre energy levels become closer together as they do in the line spectrum. Light is emitted when excited electrons fall back to the ground level
What could Bohr’s equations allows scientists to calculate?
Radius of hydrogen atom
It’s energy levels
It’s ionisation energy
What was the main problem for faced with his equations?
The behaviour of atoms with more than one electron
What property of light is the energy of light related to?
Frequency of light
The emission spectra only consists of a limited number of frequencies. What does this tell us about the atom?
Only a limited number of energy changes or transitions can take place within the atom
What does quantum mechanics say about the arrangement of electrons and atoms?
Arranged in a series of shells
Each shell described by the principal quantum numbers
Each shell may contain a number of subshells
What does the principal quantum number tell you about?
The size of the shell
What is ionisation?
The complete removal of an electron from an atom
Why is ionisation an endothermic process?
What must be done on an electron in order to overcome the attractive forces between it and the nucleus
How are ionisation energy is measured?
Gradually increasing the voltage applied to a gas until it conducts electricity and emits light
What does it mean when we say an atom is in its ground state?
It is at its lowest energy level
What are the units for ionisation energies?
kJmol(-1)
What is the first ionisation energy a measure of?
How tightly the outer electron is attracted to the positive nucleus
Will not with a lower first ionisation energy be more or less reactive than one with the higher first ionisation energy?
More
How do you calculate the energy needed to go from the magnesium atom to a magnesium 2+ ion?
The amount of energy needed to remove the first electron to the amount needed to remove the second
What is an orbital?
The region where the electrons are most likely to be found
How do you calculate the number of subshells?
Number of shell
How do you calculate the number of orbitals?
Number of shells squared
Two electrons in an orbital must have the same/different spin
Different
Why are each of the P orbitals filled with one electron before pairing electrons up?
Electrons repel each other and they spread out to maximise the number unpaired electrons
Why is the for 4s orbital fields before 3d?
It is at a lower energy level
Why are inner electrons is not involved in chemical bonding?
They are strongly attracted to the nucleus
The model of the behaviour of electrons wideness accepted by scientists consider electrons as waves/particles
Waves
What is an electron cloud?
Electrons spread out around the nucleus
What do maps of the electron density of electron clouds show us?
The shapes of the areas in spaceworthy electron is likely to be
What happens to the size of the orbitals as principal quantum number increases?
The size of the P and S orbitals increase
Can you draw the shapes of the orbitals?
Go look it up yourself
What determines the blocks that the periodic table is split up into?
Which electron orbitals being filled
Which groups make up the S block elements?
1 and 2
Why are groups one and two known as the s block elements elements?
The outermost electrons are in the S subshells
Give 4 properties of the S block elements
Very reactive
Low melting and boiling point
Low densities
Conduct electricity
Why are hydrogen and helium not considered part of the S block elements even though they have their outer electrons in the S orbitals?
They have different properties to the other elements
What are the d block elements often referred to as?
The transition metals
Why are the transition metals much less reactive than the S block elements?
In a D orbitals are being filled while the outer S subshell is full
Give three properties of the D block elements
Conducts heat and electricity
Hard and shiny
Malleable
What are the elements in the top row of the F block elements called?
Lanthanides
What are the elements in the second row of the F block elements called?
Actinides
Which are radioactive? The actinides or the lanthanides
Actinides
Elements are contained within the P block?
All the nonmetals apart from hydrogen and helium and metalloids as well as some metals
Give two properties of the pibroch metals
Conduct heat and electricity
Post-transition metals are relatively unreactive
Which important property of metals do the metalloids have?
Conduct electricity
What type of bonds do non-metals form with non-metals?
Covalent
What type of bonds do non-metals form with metals?
Ionic
What are the repeating patterns in the periodic table known as?
Periodicity
What are the repeating properties of the elements in the periodic table know as?
Periodic properties
Why does atomic radius decrease across a period?
The electrons in the outer shell of pulled closer to the nucleus due to an increase nuclear charge
Why does atomic radius increases as you go down a group?
Electrons are not held so tightly because the force of attraction is shielded by other electrons
They are further away
Why do positive ions have a smaller radius than the ions from which they are formed?
The remaining electrons each have a greater share of the positive charge so more tightly bound
Usually when an ion is formed a whole electron shell is lost
Why do negative ions have a larger radius than the atom from which they are formed?
The addition of extra negative charge means that the electrons are less tightly bound to the nucleus
What is the first ionisation energy of an element directly related to?
Attraction of the new class for the most loosely bound of the outer electrons
What are the three main factors that affect the ionisation energy of an atom?
Attraction between nucleus and outermost electron
Size of positive nuclear charge
In the shells of electrons repelling other electrons or shielding the force of attraction
Why does ionisation energy increase across a period?
Increasing positive nuclear charge across the period without the addition of any extra shells to shield outer electrons
What is the evidence for sub shells?
The first ionisation energies of the elements do not increase smoothly across a period
Why does ionisation energy decrease down a group?
Electrons become further away and the force of attraction is shielded by inner electrons which means that less energy is required to remove electrons
What is the melting temperature of an element affected by?
The packing and the bonding of atoms in a substance
Why do lithium, magnesium and aluminium have relatively high melting temperatures?
It takes a lot of energy to separate atoms as they are held tightly in a sea of electrons
Why do carbon and silicon have such high melting temperatures?
Held together with ionic bonds in giant lattices
Why do you nitrogen, oxygen and fluorine have low melting temperatures?
There are strong covalent bonds within the molecules however the molecules only held together by weak–molecular forces
