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Development of the atomic theory The idea that everything is made up of a few simple parts originated during
the 400's B.C. in the philosophy of atomism. Atomism was founded by the Greek philosopher Leucippus, but his disciple Democritus developed the philosophy more fully. Democritus gave his basic particle the name ……., which means …………………... He imagined atoms as small, hard particles, all composed of the same substance but of different sizes and shapes. During the 300's B.C., a Greek philosopher named Epicurus incorporated Democritus's ideas about atoms into his philosophy. About 50 B.C., the Roman philosopher and poet Lucretius presented the fundamental principles of atomism in his long poem, On the Nature of Things.
During the Middle Ages, the idea of atoms was largely ignored. This neglect resulted partly from the fact that atomism had been rejected by Aristotle, an ancient Greek philosopher whose theories dominated medieval philosophy and science. The idea that atoms form the ……………………….. of all matter did survive, however. During the 1500's and 1600's, such founders of modern science as Francis Bacon and Isaac Newton of England and Galileo of Italy believed in atoms. But those scientists could add little more to the atomic theory than Democritus had described.
Development of the atomic theory The idea that everything is made up of a few simple parts originated during
the 400's B.C. in the philosophy of atomism. Atomism was founded by the Greek philosopher Leucippus, but his disciple Democritus developed the philosophy more fully. Democritus gave his basic particle the name atom, which means uncuttable. He imagined atoms as small, hard particles, all composed of the same substance but of different sizes and shapes. During the 300's B.C., a Greek philosopher named Epicurus incorporated Democritus's ideas about atoms into his philosophy. About 50 B.C., the Roman philosopher and poet Lucretius presented the fundamental principles of atomism in his long poem, On the Nature of Things.
During the Middle Ages, the idea of atoms was largely ignored. This neglect resulted partly from the fact that atomism had been rejected by Aristotle, an ancient Greek philosopher whose theories dominated medieval philosophy and science. The idea that atoms form the basic units of all matter did survive, however. During the 1500's and 1600's, such founders of modern science as Francis Bacon and Isaac Newton of England and Galileo of Italy believed in atoms. But those scientists could add little more to the atomic theory than Democritus had described.
The birth of the modern atomic theory.In 1750, Rudjer Boscovich, a scientist born in what is now Croatia,
suggested that Democritus might have been wrong in believing that atoms are "uncuttable." Boscovich thought that atoms contain smaller parts, which in turn contain still smaller parts, and so forth down to the fundamental building blocks of matter. He felt that these building blocks must be geometric points with no size at all. Today, most atomic physicists accept a modern form of this idea.
The development of the atomic theory advanced greatly when chemistry became an exact science during the late 1700's. Chemists discovered that they could combine elements to form compounds only in certain ……… proportions according to …….. In 1803, a British chemist named John Dalton developed an atomic theory to explain this discovery.
The birth of the modern atomic theory.In 1750, Rudjer Boscovich, a scientist born in what is now Croatia, suggested that
Democritus might have been wrong in believing that atoms are "uncuttable." Boscovich thought that atoms contain smaller parts, which in turn contain still smaller parts, and so forth down to the fundamental building blocks of matter. He felt that these building blocks must be geometric points with no size at all. Today, most atomic physicists accept a modern form of this idea.
The development of the atomic theory advanced greatly when chemistry became an exact science during the late 1700's. Chemists discovered that they could combine elements to form compounds only in certain FIXED proportions according to MASSIn 1803, a British chemist named John Dalton developed an atomic theory to explain this discovery. *
* Information taken from a variety of sources – including Wikipedia.
Atomic Theory PresentationMany scientists contributed to the development of the modern atomic theory,
including: Dalton, Thomson, Rutherford, Chadwick, Bohr, De Broglie, Schrodinger, Heizenberg, Pauli
Research the contribution of any one of the scientists listed above and present your findings in a 3 minute presentation.
• You must use the headings applicable to any scientific investigation: – Theory/Background, Aim, Apparatus, Method/Experiments, Results,
Conclusions,
– If no information is available for a particular heading then just state “No information available.”
– Evaluation (Yours): Give your impression of the impact the particular person had on atomic theory development.
Information can be taken from lessons or your textbooks as well as other sources BUT must be given in your OWN WORDS!
ATOMIC THEORY PRESENTATION RUBRIC NAME: ________________________
ITEMS Required Detail MARKS>> 0 1 2 3 MARK
Scientist chosen from list:
Dalton, Thomson, Rutherford, Chadwick, Bohr, De Broglie, Schrodinger, Heizenberg, Pauli
No Yes
Timing 3 minutes <1 / >5
1/5 2/4 3
Presentation SkillsEye contact, knowledge, confidence, voice intonation, engaging/dynamic
nonesom
emost all
Presentation AidsAppropriate/correct, neat, attractive, stimulating, variety
nonesom
emost all
Scientific Investigation Headings
Theory/Background, Aim, Apparatus, Method/Experiments, Results, Conclusions,
nonesom
emost all
Evaluation personalOwn impression, impact on atomic theory development, coherent reasoning, impressive/thoughtful
nonesom
emost all
Evidence of own input % which appears original nonesom
emost all
TOTAL
The birth of the modern atomic theory.
Dalton proposed that each element consists of a ……………. ……………..of atom and that the varying properties of the elements result from differences in their atoms.
He further suggested that all atoms of a given element are ………………….. in size, shape, and mass.
According to Dalton's theory, when atoms combine and form a particular compound, they always combine in a …………… ………………………. As a result, the composition by mass of a particular compound is always the same.
The birth of the modern atomic theory.
Dalton proposed that each element consists of a particular kind of atom and that the varying properties of the elements result from differences in their atoms.
He further suggested that all atoms of a given element are identical in size, shape, and mass.
According to Dalton's theory, when atoms combine and form a particular compound, they always combine in a specific numerical ratio. As a result, the composition by mass of a particular compound is always the same.
The electrical nature of matter• Thompson’s experiments
with …………… ray tubes led to the discovery of ……………. in atoms.
• He advanced the model of the atom to include positive and negative charges in the “…………………..” model.
The electrical nature of matter• Thompson’s experiments
with cathode ray tubes led to the discovery of charges in atoms.
• He advanced the model of the atom to include positive and negative charges in the “current bun” model.
Radioactivity• Radioactivity is the ............................ emission of
…………………….(sub atomic particles) from some materials.
• The discovery of radioactivity led to the realization that atoms were …………………….
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
Radioactivity• Radioactivity is the spontaneous emission of radiation (sub atomic
particles) from some materials. Marie Curie• The discovery of radioactivity led to the realization that atoms were
not indivisible.
Radioactivity• While she was studying for her doctorate, Henri Becquerel sent her
samples of a uranium salt that had left an impression on x-ray film, .......................................................... in which they were contained.
• Do you have a watch with hands that glow? Radium was the first substance used to make the watch hands glow. Women were hired to brush radium paint onto the tiny watch hands. The problem was that the brush head was unmanageable and the women licked the brush to keep the head nice and pointy. Their tongues eventually fell off, and that was only the beginning. ..........................and ......................... followed. And then eventually death.
• With Radium selling at ........................................ a pound (back in the twenties) doctors everywhere were investing in this wonderful cancer cure. A “cure” that caused cancer and leukemia.
Radioactivity• While she was studying for her doctorate, Henri Becquerel sent her
samples of a uranium salt that had left an impression on x-ray film, through the envelope in which they were contained.
• Do you have a watch with hands that glow? Radium was the first substance used to make the watch hands glow. Women were hired to brush radium paint onto the tiny watch hands. The problem was that the brush head was unmanageable and the women licked the brush to keep the head nice and pointy. Their tongues eventually fell off, and that was only the beginning. Leukemia and bone cancer followed. And then death.
• With Radium selling at ten million dollars a pound (back in the twenties) doctors everywhere were investing in this wonderful cancer cure. A “cure” that caused cancer and leukemia.
Rutherford’s experiment• Rutherford shot ................... particles at very thin gold
foil.• Most of the radiation ........................................• Some radiation was .................................. - by significant
amounts.
Rutherford’s experiment• Rutherford shot alpha particles at very thin gold foil.• Most of the radiation went straight through.• Some radiation was deflected - by significant
amounts.
Rutherfords ModelRutherford’s model has the
electrons moving in orbits around a very dense core.
• The core consists of ................ (....) - this would have caused the massive ........................... he had observed.
• The ........................... orbit at a large distance from the nucleus - this explains why much of the radiation ..............................the gold foil.
• No of electrons = no. of protons
Protons - in the nucleus
electrons
Rutherfords ModelRutherford’s model has the electrons
moving in orbits around a very dense core.
• The core consists of protons (+) - this would have caused the massive deflections he had observed.
• The electrons orbit at a large distance from the nucleus - this explains why much of the radiation passed through the gold foil.
• No of electrons = no. of protons
Protons - in the nucleus
electrons
Rutherfords Model - problemsRutherford’s model could not
explain:
• Why the electrons did not lose energy as they orbited.
• What held the protons together in the nucleus.
• The origins of __________ _______ of gases could not be explained.
Protons - in the nucleus
electrons
Rutherfords Model - problemsRutherford’s model could not
explain:
• Why the electrons did not lose energy as they orbited.
• What held the protons together in the nucleus.
• The origins of emission spectra of gases could not be explained.
Protons - in the nucleus
electrons
Atomic Structure RevisionELEMENT SYMBOL Z (ATOMIC
NUMBER)A (MASS NUMBER)
NEUTRONS ELECTRONS
TOT VALENCE
Hydrogen H 1 1 0 1 1
Lithium Li 3 7 4 3 1
Carbon C 6 12 6 6 4
Nitrogen N 7 14 7 7 5
O
Ne
Na
Ar
Ca
Fill in the missing information for each of the elements above – note any patterns that begin to develop.
Atomic Structure RevisionELEMENT SYMBOL Z (ATOMIC
NUMBER)A (MASS NUMBER)
NEUTRONS ELECTRONS
TOT VALENCE
Hydrogen H 1 1 0 1 1
Lithium Li 3 7 4 3 1
Carbon C 6 12 6 6 4
Nitrogen N 7 14 7 7 5
O
Ne
Na
Ar
Ca
Fill in the missing information for each of the elements above – note any patterns that begin to develop.
THE NEUTRAL ATOM
Notation
Z
AXAtomic Number
(smaller)
Mass Number (bigger) symbol
• Atomic Number Z = number of protons (& electrons)
• Mass number A = protons + neutrons.
• Number of neutrons = A - Z
Line Spectra
Gases absorb certain frequencies of light.
Each gas absorbs a unique combination of frequencies – each frequency corresponding to a unique colour.
So each gas has a unique set colours which is known at its “line spectra” – because they are unique they can be used to identify a gas – similar to fingerprints.
Line SpectraGases absorb certain frequencies of light.
Each gas absorbs a unique combination of frequencies – each frequency corresponding to a unique colour.
So each gas has a unique set colours which is known at its “line spectra” – because they are unique they can be used to identify a gas – similar to fingerprints.
Bohr’s AtomBohr - brought the concept of
quantization into atomic theory.Electrons could only move in certain
specific orbits corresponding to specific amounts of energy.
These ENERGY LEVELS radiated out from the nucleus with higher energies being further away.
Electrons do not radiate energy in these orbits.
Energy is gained or lost when they move between orbits.
This model enabled Bohr to explain the hydrogen spectrum.
Atomic SpectraA glass prism can be used to generate a colour …………………..
If this the light generated by a hot (glowing) gas is viewed through a prism specific colour lines are seen as AN ……………… ………….SPECTRUM.
If light is shone through a cold sample of the same gas, the same specific colour lines are absent and appear as an ……………………….. LINE SPECTRUM.
Atomic SpectraA glass prisim can be used to generate a colour spectrum.
If this the light generated by a hot (glowing) gas is viewed through a prism specific colour lines are seen as AN EMISSION LINE SPECTRUM.
If light is shone through a cold sample of the same gas, the same specific colour lines are absent and appear as an ABSORPTION LINE SPECTRUM.
Absorption & Emission spectrum
• In absorption spectrum radiation is again absorbed by electrons being …………… to higher energy levels.
• The same frequencies (colours) are again emitted when the excited electrons ……………………. to the ground state in an ………………………spectrum.
---- …………………………………………………
Absorption & Emission spectrum
• In absorption spectrum radiation is again absorbed by electrons being excited to higher energy levels.
• The same frequencies (colours) are again emitted when the excited electrons drop down to the ground state in an emission spectrum.
---- EMITTED LIGHTABSORBED LIGHTABSORBED LIGHT
Emission SpectrumExcited electrons dropping down from unstable energy levels ……………………..in the form of light.
The frequency (colour) of the radiation is directly related to the ……………………….. between the energy levels.
Since each element has its own ……………………series of energy levels, each element also has its own unique series of …………………………… lines.
The line spectrum can therefore be used to …………………each element much like a fingerprint.
Emission Spectrum
Excited electrons dropping down from unstable energy levels radiate energy in the form of light.
The frequency (colour) of the radiation is directly related to the energy gap between the energy levels.
Since each element has its own unique series of energy levels, each element also has its own unique series of emission/absorption lines.
The line spectrum can therefore be used to identify each element much like a fingerprint.
THE NEUTRAL ATOM• The atom consists of a _____________________
______________________________ surrounded by a __________________________.
• Atomic Number Z: ___________________ in the Nucleus = _________________ in a ______ atom.
• Mass number A - Number of ______ + ________
Notation
Z
AX______________ Number
(smaller)
___________ Number (bigger) symbol
THE NEUTRAL ATOM• The atom consists of a nucleus containing protons
and neutrons surrounded by a cloud of electrons.
• Atomic Number Z - Number of protons in the Nucleus = number of electrons in a neutral atom.
• Mass number A = Number of protons + neutrons.
Notation
Z
AXAtomic Number
(smaller)
Mass Number (bigger) symbol
Relative Masses• Relative atomic(Ar): The mass of the atom relative to
________________________________________. (Number of times heavier than…)
Eg: O - 16 one atom of oxygen is ________________ than 1/12 of the mass of a C12 atom,
Formula mass (Mr) - The _______________________ of the atoms in a molecule.
Water H2O one molecule of water has a relative mass of _____________________________ that is the molecular or formula mass of water.
Mr(H2O) = 18 (Times heavier than…)
Relative Masses
• Relative atomic mass (Ar): The average mass of an atom of an element relative to 1/12 of the mass of a C12 atom. (Number of times heavier than…)
Eg: O - 16 one atom of oxygen is 16 times heavier than 1/12 of the mass of a C12
atom.
• Formula mass (Mr) - The sum of all the atomic masses of the atoms in a molecule.
Water H2O one molecule of water has a relative mass of (2x(1)+16) = 18 - that is the molecular or formula mass of water.
Mr(H2O) = 18 (Times heavier than…)
Relative Masses - examples
Calculate the Formula masses of:• O2 (oxygen gas) Mr(O2) = • Cl2 (chlorine gas)• NaCl (sodium chloride - table salt)
• CaCO3 (calcium carbonate)
• (NH4)2Cr2O7 (ammonium dichromate)
Relative Masses - examples
Calculate the Formula masses of:• O2 (oxygen gas) Mr (O2) = 2x16 = 32• Cl2 (chlorine gas) Mr (Cl2) = 2x35.5 = 71.0• NaCl (sodium chloride - table salt)
Mr (NaCl) = 23+35.5 = 58.5• CaCO3 (calcium carbonate)
Mr (CaCO3) = 40.1+12+(3x16) = 100.1• (NH4)2Cr2O7 (ammonium dichromate)
Mr ((NH4)2Cr2O7 ) = 2(14+4)+2(52)+7(16) = 252
Isotopes
Isotopes Atoms of the same element which have different numbers of
neutrons. Others – Boron 10 & 11, Hydrogen 1 & 2, Chlorine 35 & 37. Write notation and work out numbers of neutrons.
e- e-
e- e-e-
e- e- e-
e- e-e-
e-
The two atoms below both belong to carbon but they are not identical – can you spot what is different?
612C 6
13C
Isotopes
Isotopes Atoms of the same element which have different numbers of
neutrons. Others – Boron 10 & 11, Hydrogen 1 & 2, Chlorine 35 & 37. Write notation and work out numbers of neutrons.
e- e-
e- e-e-
e- e- e-
e- e-e-
e-
The two atoms below both belong to carbon but they are not identical – can you spot what is different?
612C 6
13C
510B 5
11B 1735Cl 17
37Cl 11H 1
2H
Isotopes• Isotopes - Atoms of the _______________ which
have different _____________________________________.
Eg: 613C & 6
12C
• 37Cl (25%) & 35Cl (75%) - ratio _________
Av Ar(Cl) =
Or
Av Ar(Cl) = Relative atomic mass is (actually) the ____________ mass of an atom of an element
relative to 1/12 of the mass of a carbon-twelve atom.
Isotopes• Isotopes - Atoms of the same element which have
different numbers of neutrons. Eg: 613C & 6
12C
• 37Cl (25%) & 35Cl (75%) - ratio 1:3
Av Ar(Cl) = (37x25)+(35x75) = 35.50100Or
Av Ar(Cl) = (37x1)+(35x3) = 35.504
Relative atomic mass is (actually) the average mass of an atom of an element relative to 1/12 of the mass of a carbon-twelve atom.
Bohr’s Atom - problems• Only explain ____________
_______________
• Could not explain __________ _______________________ or formation or properties.
• Why ________________ and ___________________ in orbits.
• At variance with ___________ ______________________.
Heisenberg: Not possible to know _________________________________ at the same _______________ with the same _______________________.
Bohr’s Atom - problems• Only explain hydrogen
spectrum.
• Could not explain molecules (bonding of atoms) - formation or properties.
• Why fixed orbits and no energy radiation in orbits.
• At variance with Heisenberg’s uncertainty principle.
Heisenberg: Not possible to know both the position and velocity of an electron at the same time with the same amount of accuracy.
A Wave Model• De Broglie - light - ‘_____
______________’ - theory.
• Davisson & Germer - electron diffraction -proof of ‘__________________’.
• Shroedinger, Heisenberg et. al. - __________________ mechanical model.
• Orbits ---> ________________- standing electron ____________ - a ___________________ defining the standing wave pattern.
Orbital: - a region where there is a __________________ of finding an electron.
A Wave Model• De Broglie - light - ‘matter
wave’ - theory.• Davisson & Germer - electron
diffraction -proof of ‘matter waves’.
• Shroedinger, Heisenberg et. al. - wave & quantum mechanical model.
• Orbits ---> Orbitals - standing electron waves - a region or space defining the standing wave pattern.
Orbital: - a region where there is a high probability of finding an electron.
Ionisation Energy (Ei)The ____________________________ to REMOVE AN ELECTRON completely from an atom.
Na: 1s22s22p63s1 Na+: 1s22s22p6Electronic structure
FIRST ionisation energy (Ei1): Energy required to remove _______________ electron. ______ ____________
SECOND ionisation energy (Ei2): Energy required to remove ____________ __________ electron. ______ ____________
Ionisation Energy (Ei)The ENERGY REQUIRED to REMOVE AN ELECTRON completely from an atom in the GAS phase.
Sodium atom
Sodium ion
Na: 1s22s22p63s1 Na+: 1s22s22p6Electronic structure
FIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M(g) M+ (g) + 1e-
SECOND ionisation energy (Ei2): Energy required to remove SECOND OUTERMOST electron. M+(g) M2+(g) + 1e-
Successive Ionization EnergiesAnalyse this graph in light of your knowledge of atomic & electronic structure. This graph can be used to provide ‘evidence’ for some of the features of modern atomic theory.
What can be inferred about the electronic structure of the atom?
4s
3s
2s
1s
3p
2p
Al 1s2
What can be inferred about the electronic structure of the atom?
Successive Ionization EnergiesFIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M M+ + 1e-
SECOND ionisation energy (Ei2): Energy required to remove SECOND OUTERMOST electron. M+ M2+ + 1e-
Inner level
Hard to remove close to nucleus
Second energy level
Outer (valence) level
Easy to remove far from the nucleus
This graph provides EVIDENCE for energy levels.
What can be inferred about the electronic structure of the atom?
Successive Ionization EnergiesFIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M M+ + 1e-
SECOND ionisation energy (Ei2): Energy required to remove SECOND OUTERMOST electron. M+ M2+ + 1e-
Inner level
Hard to remove close to nucleus
Second energy level
Outer (valence) level
Easy to remove far from the nucleus
This graph provides EVIDENCE for energy levels.
FIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M M+ + 1e-
First Ionisation Energies
Identify any trends or patterns in this graph.
What does this graph tell us about the electronic structure of the atom?
Patterns in EnergiesFIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M M+ + 1e-
Patterns in EnergiesFIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M M+ + 1e-
pss
FIRST ionisation energy (Ei1): Energy required to remove OUTERMOST electron. M M+ + 1e-
Patterns in First Ionization Energies (Ei1)
Patterns in First Ionization Energies (Ei1)PATTERN REASON
1 General decrease down a group
Atomic radius increases – outer shell is full so next e- is forced to enter a new energy level further from nucleus – less strongly attracted.
EVIDENCE FOR ENERGY LEVELS!!
2 General increase across a period
Increased nuclear charge – electrons in same energy level – MORE STRONGLY ATTRACTED by greater number of protons.
EVIDENCE OF – THE NUMBER OF e- IN EACH LEVEL
Patterns in First Ionization Energies (Ei1)PATTERN REASON
1 General decrease down a group
Atomic radius increases – e- further from nucleus – less strongly attracted.
2 General increase across a period
Increased nuclear charge – electrons in same energy level – MORE STRONGLY ATTRACTECD.
3 Third element’s Ei1 in a period is LOWER than second.
Outer electron in third element enters a NEW SUB LEVEL!
4 Sixth element’s Ei1 is LOWER than the fifth.
Outer element in sixth is PAIRED.
First Ionisation Energies
H
1 proton
1s
H’s electron would be removed.
Which of the following electrons would be easier to remove?
Bohr Orbits - energy levels
N = 4
N = 3
N = 2
N = 1
Electron StructureEnergy sub levels and orbitals
1s orbital
2s
2p orbitals3s
3p orbitals4s
4p (3d orbitals)
Pauli:– Electrons occupy _____
______________ levels.
– Max ____________ per orbital
– ______________ occurs when two electrons sharing the same orbital.
Electron distributionEnergy levels (1,2,3 etc) are divided up into ______________________ each of which has a specific number of orbitals
(s-___, p-____, d- ____).
N N=1 first energy level
N=2 second energy level
Pauli’s Exclusion Principle:– Electrons occupy lowest
vacant energy levels.
– Max two electrons per orbital
– spin paring occurs when two electrons sharing the same orbital.
Electron distributionEnergy levels (1,2,3 etc) are divided up into sub-levels (s, p, d, f) each of which has a specific number of orbitals
(s-1, p-3, d-5).
N
S N
S
N=1 first energy level
N=2 second energy level
Electron Structure Afbau Diagrams
1s
4s
3s
2s
1s
3p
2p
H: 1s1He: 1s2
Hydrogen has only one electron so it would go into the first available orbital – the 1s orbital.
It takes less energy to spin pair than to move to a new energy level so Helium would have two electrons in the 1s orbital.
Protons 1 Protons 2
Electron Structure – Aufbau Diagrams
4s
3s
2s
1s
3p
2p
4s
3s
2s
1s
3p
2p
Li 1s2 2s1 Be 1s2 2s2
S, p, d notation
Electron Structure
4s
3s
2s
1s
3p
2p
4s
3s
2s
1s
3p
2p
Al 1s2 2s2 2p6 3s2 3p1
Si 1s2 2s2 2p6 3s2 3p2
Electron Structure
4s
3s
2s
1s
3p
2p
4s
3s
2s
1s
3p
2p
P 1s2 2s2 2p6 3s2 3p3
-----------------------------
Cl 1s2 2s2 2p6 3s2 3p5
Ei Trends in a group
4s
3s
2s
1s
3p
2p
Li 1s2 2s1
4s
3s
2s
1s
3p
2p
Na 1s2 2s2 2p6 3s1
OUTER ELECTRON FURTHER FROM NUCLEUS – LESS ENERGY REQUIRED TO REMOVE IT – LOWER EI1
COMPLETE INNER LEVELS SHIELD THE OUTER ELECTRONS FROM THE EFFECTS OF THE INCREASED NUCLEAR CHARGE
3 PROTONS 11 PROTONS
FIRST Ei DECREASES DOWN A GROUP!
Electron Structure
4s
3s
2s
1s
3p
2p
4s
3s
2s
1s
3p
2p
B 1s2 2s2 2p1
C 1s2 2s2 2p2
Ei1 INCREASES
5 PROTONS6 PROTONS!
FIRST IONISATION ENERGY INCREASES FROM L R ACROSS A PERIODATOMIC RADIUS DECREASES BECAUSE ELECTRONS ARE MORE STRONGLY ATTRACTED BY THE INCREASED NUCLEAR CHARGE!!! MORE ENERGY REQUIRED TO REMOVE THE OUTER ELECTRON! GREATER FIRST IONIZATION ENERGY!!
Third IE lower than Second!
4s
3s
2s
1s
3p
2p
Be 1s2 2s2
4s
3s
2s
1s
3p
2p
B 1s2 2s2 2p1
3 protons 4 protons
New sublevel (p) slightly higher in energy – less strongly attracted – slightly less energy required to remove!