Atomic Structure

Atomic Size radius •Order of magnitude – (10-10 – 10-12)m •Radius Li atom – (1.5 x 10-10)m •Radius nucleus – (1 x 10-14)m

1nm – 1 x 10-9 m 1pm – 1 x 10-12 m 1A - 1 x 10-10 m

Radius Li

atom

Radius Nucleus

Li atom Elementary particles making up nucleon (protons + neutrons)

Nucleon –made up of (protons + neutrons) Protons – made up of 2 up quarks + 1 down quark Neutron – made up of 2 down quarks + 1 up quark

Unit conversion

Structure within atom

Recent discovery particles with help of Large Hadron Collider

Video on new particles physics

http://astronomyonline.org/ViewImage.asp?Cate=Home&SubCate=MP01&SubCate2=&Img=%2FScience%2FImages%2FAtomicStructure.jpg&C

pt

http://justintymewrites.wordpress.com/2012/06/20/the-standard-model-in-laymans-terms2/

Discovery timeline Democritus to Quantum model

Video on timeline discovery

Discovery of elementary particles Elementary particles

Structure within atom

Video on new particles physics

Recent discovery particles from Large Hadron Collider

Higgs boson leftover excitation of particles of Higgs field

Discovery of Higgs boson and Higgs field

Particles interact with Higgs field to produce mass

Video on Higgs field part 1

Video on Higgs field part 2

Higgs Boson Discovery Wins Nobel Prize for Physics

Video on NOBEL PRIZE 2013 !!!!!!

Atomic Structure

Atomic Size radius •Order of magnitude – (10-10 – 10-12)m •Radius Li atom – (1.5 x 10-10)m •Radius nucleus – (1 x 10-14)m

Scale/size of matter from smallest to largest

Excellent Flash on scale of universe Excellent Flash on biological cells Video on scale of universe

1nm – 1 x 10-9 m 1pm – 1 x 10-12 m 1A - 1 x 10-10 m

Radius Li

atom

Radius Nucleus

Li atom Elementary particles making up nucleon (protons + neutrons)

Nucleon –made up of (protons + neutrons) Protons – made up of 2 up quarks + 1 down quark Neutron – made up of 2 down quarks + 1 up quark

Unit conversion

Elementary particles Structure within atom

Recent discovery particles from Large Hadron Collider

Higgs boson leftover excitation of particles of Higgs field

Discovery of Higgs boson and Higgs field

Particles interact with Higgs field to produce mass

Video on Higgs field

Mass (proton + neutron)- due to interaction between up quarks/down quarks with gluons (energy fluatutions)

Proton -2 up quarks

1 down quark

Neutron -1 up quark

2 down quarks

What is Higgs Boson ? What is Higgs Field ?

Excellent videos –Particles interact with Higgs field to create MASS

Video (Ted Talk) Video (Minute physics) Video (RI) Video (Veratasium)

Nuclear reaction vs Chemical reaction

Nuclear reaction • Involve protons/neutrons in nucleus • Decomposition of nucleus into smaller nuclei • Energy released greater • Conservation of charge / atomic mass number

Chemical reaction • Involve outer most electrons • Transfer/sharing/loss of electrons • Energy released less • Conservation of mass and charge

2Na + CI2 2NaCI

http://ths.talawanda.net/~BrambleN/classroom/Chemistry/Notes/Section%206A%20and%206B/RadioactiveDecay.htm

http://www.classhelp.info/Biology/AUnit3Biochemistry.htm

Type radiation

Nature radiation

Symbol Penetration (mass,m/charge,e

)

Ionising power (removing electron)

Alpha Helium nucleus

α Low ratio (high m/e)

High

Beta High energy electron

β Moderate Moderate

Gamma High frequency electromagnetic

radiation

γ High ratio (small m/e)

Low

Type of radiation

Nuclear equation- decay of nucleus Chemical equation – valence electrons

Transfer electrons

Sharing electrons

Nuclear reaction

http://ths.talawanda.net/~BrambleN/classroom/Chemistry/Notes/Section%206A%20and%206B/RadioactiveDecay.htm

http://molaire1.perso.sfr.fr/e_radioactiv.html

Alpha Decay •Losing an alpha particle – helium nucleus •Daughter nuclei lower in proton number •Mass of 4 (2 proton + 2 neutron) •+2 charged (only 2 protons) = +2 •Decay of uranium, thorium, actinium

Beta Decay •Losing beta particle –Electron/positron •Daughter nuclei higher in proton number •Negative charge (-1) •Decay neutron proton + electron

Alpha Decay Beta Decay

Gamma Decay

Gamma decay •Losing a γ particle - electromagnetic radiation of high frequency •Daughter nuclei no change in atomic mass

α β

Unstable nucleus of atom Decay by emitting ionizing particles

+

Difference Between Alpha, Beta and Gamma Radiation

Alpha Decay •Lose alpha particle – helium nucleus •Mass He- 4 (2 proton + 2 neutron) •+2 charged (2 proton + 2 neutron + 0 e) •Daughter nuclei lower in proton number

Beta Decay •Lose beta particle –Electron/beta β •Negative charge (-1) •-1 charged (β or electron) •Daughter nuclei higher in proton number

Gamma decay •Lose a γ particle – electromagnetic radiation of high frequency •Daughter nuclei no change in atomic mass

Nucleus > 84 protons • Unstable, radioactive decay • Decay depends on ratio neutron/proton

Decay depend on ratio neutron/proton Neutron/proton ratio LOW – Proton rich – Decay to reduce proton - Alpha decay, α (proton number )

Mass number always Conserved/Same

Decay depend on ratio neutron/proton Neutron/proton ratio HIGH – Neutron rich – Decay to reduce neutron -Beta decay β ( Neutron Proton + electron) -Ratio decrease

Decay depend on ratio neutron/proton Neutron/proton ratio HIGH /LOW -Gamma decay γ, is associated along with Alpha and Beta

Video on α decay Video on β decay Video on γ decay

Radioactive isotopes Half-life

Uranium 238 4.5 x 109

Carbon-14 5.7 x 103

Radium-226 1.6 x 103

Strontium-90 28 years

Iodine-131 8.1 days

Bismuth-214 19.7 minutes

Polonium-214 1.5 x 10-4

Isotopes

Stable Isotopes Unstable Isotopes

Unstable Isotopes – emits radiation

RADIOISOTOPES

Simulation isotope 12C, 13C, 14C

Radioisotopes •Half-life – time taken for conc/amt isotope to fall to half of its original value. •Half life decay – always constant

Shorter half-life More unstable, decay fast

Long half-life More stable, decay slowly

www.sciencelearn.org.nz

Emit radiation form unstable isotope

Simulation isotope 1H, 2H, 3H

Video on Half life

Simulation half life C-14/uranuim

Half-life

Carbon – 3 Isotopes Radiocarbon/carbon dating

• Half life C-14 = 5730 years • Beta (β/electron ) decay

Conclusion Ratio C14/C12 is constant is organism alive Ratio C14/C12 drop organism die

Uses • Age dead organic material/fossil contain Carbon element • Max age limit is 60,000 years old.

Carbon -12 Carbon -14 Carbon -13

Abundance – 99% (Stable) Abundance – 1% (Stable) Abundance – trace amt (Unstable , radioactive)

How is form? • C-14 produce in stratosphere when….. neutron hit a nitrogen atom to form C-14 •C-14 to N-14 by converting neutron proton (proton stay in nucleus), electron emit as β radiation • emit as β ray.

(proton in nucleus – increase proton number)

emit as β ray. •Ratio C14/C12- constant if alive – TAKE in C14 (C12 constant) •Ratio C14/C12- drop if dead - NOT taking C14. (C12 constant)

How it is form?

Radiocarbon/carbon dating

• Half life C-14 = 5730 years • Beta (β/electron ) decay

Carbon -14

Abundance – trace amt (Unstable , radioactive)

How is form? • C-14 produce in stratosphere when….. neutron hit a nitrogen atom to form C-14 •C-14 to N-14 by converting neutron proton (proton stay in nucleus), electron emit as β radiation • emit as β ray.

(proton in nucleus – increase proton number)

emit as β ray. •Ratio C14/C12- constant if alive – TAKE in C14 (C12 constant) •Ratio C14/C12- drop if dead - NOT taking C14. (C12 constant)

Video on C-14 Carbon Dating Video on C-14 Carbon Dating/Fossil Video on C-14 Half life Carbon Dating

Simulation C-14 (Half life) At 100% (Starting)

Simulation C-14 (Half life) At 50% (Starting)

Video on Radiocarbon dating

Click to view simulation

How Radiocarbon dating works?

Radiocarbon/carbon dating

• Half life C-14 = 5730 years

Carbon -14

Beta (β/electron) decay

Video on C-14 Carbon Dating

Video on Radiocarbon dating

How Radiocarbon dating works?

Uses of radioactive isotopes

Radiotherapy/cancer/tumour Tracers/studying metabolic pathways

Cobalt-60

• Half life Co-60 = 5.27 years • Half life I-131 = 8 days

How Gamma rays works? How Radio tracer works?

Iodine-131

Sterilization – killing bacteria/germ Radiotherapy – kill tumor cells High energy electromagnetic ray

Video on Radio tracer Video on Radiotherapy

Gamma γ + β decay

Carbon dating Age of fossil remains

• Radio tracer • Trace the pathway in body • Beta β (90%) and γ (10%) decay

Gamma γ + β decay

6 protons + 6 neutrons

8 protons

No isotopes are present

Proton number = proton

Mass number = proton + neutron

Z

A

Atomic /Mass number

6 protons

Atomic Weight With isotopes present

8 protons + 8 neutrons

Proton number = proton Z

Mean relative mass (atomic weight) A

Video on weighted average

Relative Atomic Mass, (Ar) of an element:

• Number of times one atom of the element is heavier than one twelfth of the mass of a carbon-12

• Relative atomic mass = Mass of one atom of element 1/12 x mass of one carbon-12

• Relative atomic mass for sulphur = 32 (one sulphur atom is 32 x heavier than 1/12 of mass of one (C12)

http://www.tutorvista.com/content/science/science-i/atoms-molecules/atom.php

Relative Atomic Mass

Carbon-12 as standard 1/12 of C12 = 1 unit

Sulphur – 32x heavier

1/12 x = 1 unit

32 unit

6 protons + 6 neutrons

16 protons + 16 neutrons

Relative Atomic Mass is used : • Impossible to weigh an atom in grams • Compare how heavy one atom is to carbon (standard) • One sulphur atom 32x heavier than 1/12 carbon -12 • Carbon -12 used as standard

12

6

32

16

No isotopes are present

Mass number = proton + neutron

Proton number = proton Z

A

Assuming No isotopes present!

Mass number ≠ Average atomic mass (atomic mass unit)

Relative Molecular Mass, (Mr):

• Number of times one molecule is heavier than one twelfth of the mass of a carbon-12

• Relative molecular mass = Mass of one molecule 1/12 x mass of one carbon-12

• Relative molecular mass for H2O= 18 (one H2O is 18 x heavier than 1/12 of mass of one (C12)

http://www.tutorvista.com/content/science/science-i/atoms-molecules/atom.php

Relative Molecular Mass is used : • Impossible to weigh an molecules in grams • Compare one molecule to carbon (standard) • One H2O is 18 x heavier than 1/12 carbon -12 • Carbon -12 is used as standard

Relative Molecular Mass

Carbon-12 as standard 1/12 of C12 = 1 unit

H2O – 18x heavier

1/12 x = 1 unit

16 unit

2 unit

18 unit

+

6 protons + 6 neutrons

8 protons + 8 neutrons

No isotopes are present

Proton number = proton

Mass number = proton + neutron

Z

A

Assuming No isotopes present!

Mass number ≠ Average atomic weight (atomic mass unit)

2 protons

Relative Isotopic Mass

Isotopes – Atoms of same element with • Different number of neutrons • Same number of protons and electrons Due to presence of isotopes, when calculating RAM,

weighted average/mean of all isotopes present is used.

X - No isotopes

RAM/Ar X = 11 • Mass of 1 atom X Mass of 1/12 of 12C • Mass of 1 atom X relative to 1/12 mass of 1 atom 12C Relative Abundance 75% 25%

Mass number = proton + neutron

Proton number = proton Z = 29 protons

A= 29 protons + 35 neutrons = 64

Isotopes Y - TWO isotopes

RAM/Ar Y = 10.5 • Average Mass of 1 atom Y Mass of 1/12 of 12C • Average mass of 1 atom Y relative to 1/12 mass of 1 atom 12C

RAM /Ar, CI = 35.5 • Weighted average mass of 2 isotopes present = (mass 35CI x % Abundance) + (mass 37CI x % Abundance) = (35 x 75/100) + (37 x 25/100) = 35.5

CI - TWO isotopes

Relative Abundance 50% 50%

Z

Presence of isotopes

A

Z

A

11

3

17

35

17

37

3 3

10 11

http://www.tutorvista.com/content/science/science-i/atoms-molecules/atom.php

Relative Atomic Mass Isotopes are present

Weighted average mass- due to presence of isotopes

Relative Isotopic Mass, (Ar) of an element: •Relative isotopic mass = Average mass of one atom of element 1/12 x mass of one carbon-12 • Relative isotopic mass, carbon = 12.01

Video on Isotopes

RAM = 12.01

Relative Abundance 98.9% 1.07%

13

Why RAM is not a whole number?

RAM, C : = (Mass 12C x % Abundance) + (Mass 13C x % Abundance) = (12 x 98.9/100) + (13 x 1.07/100) = 12.01

Video on weighted average Weighted average calculation

Video on Isotopes

RAM calculation

12

Mg - 3 Isotopes

24 Mg – (100/127.2) x 100% - 78.6% 25 Mg – (12.8/127.2) x 100% - 10.0% 26 Mg – (14.4/127.2) x 100% - 11.3%

RAM for Mg : = (Mass 24Mg x % Abundance) + (Mass 25Mg x % Abundance) + (Mass 26Mg x % Abundance) = (24 x 78.6/100) + (25 x 10.0/100) + (26 x 11.3/100) = 24.30

Relative Abundance % Abundance

Pb - 4 Isotopes

204Pb – (0.2/10) x 100% - 2% 206Pb – (2.4/10) x 100% - 24% 207Pb – (2.2/10) x 100% - 22% 208Pb – (5.2/10) x 100% - 52%

RAM for Pb : = (Mass 204Pb x % Abundance) + (Mass 206Pb x % Abundance) + (Mass 207Pb x % Abundance) + (Mass 208Pb x % Abundance) = (204 x 2/100) + (206 x 24/100) + (207 x 22/100) + (208 x 52/100) = 207.20

Convert relative abundance to % abundance

Convert relative abundance to % abundance

Relative Abundance % Abundance

Relative Atomic Mass

Simulation C-14 dating (Half life) Simulation U-238 dating (Half life)

Additional Resources

Video on isotopes using mass spec Video on Particle Physics (Higgs Field)

Simulation on atomic model

Periodic Table from webelement

Simulation isotope 1H, 2H, 3H and 12C, 13C, 14C

Excellent Video on scale of universe

Video on new particles physics

Excellent Video Higgs Field (Ted Talk)