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The Modern Theory of Atomic Structure

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Page 1: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

The Modern Theory of

Atomic Structure

Page 2: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube.

Page 3: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Particles which make up the atom are called subatomic particles.

Page 4: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Protons

Positively charged particles in

the nucleus

Neutrons - Neutral particles in the nucleus

Electrons

Page 5: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Particle Mass

(P = 1)

Charge Location

Proton

Neutron

Electron

Page 6: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Do “Instant Practice” on top of page 170

Element Symbol Atomic Number

Number of Protons

Hydrogen 1

Beryllium 4

Carbon

Cobalt

Krypton 36

Page 7: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Hydrogen-1 Hydrogen-2 Hydrogen-3

Isotopes of Hydrogen

Page 8: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Isotopes are:Different forms of the same element with the SAME # of Protons but with DIFFERENT #’s of Neutrons

Page 9: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Hydrogen-1 Hydrogen-2 Hydrogen-3

Isotopes of Hydrogen

1H 2H 3H

Page 10: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Mass Number = Total Protons + Neutrons

in an isotope of an element

3HMass Number

P + N1 P + 2 N’s

Also called “Hydrogen – 3”

Page 11: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

3H

Called the “Nuclear Notation”

Page 12: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

To find P’s and N’s from Nuclear Notation

41CaCalcium’s atomic Number = 20

So it has 20 Protons

To find # of Neutrons, put Atomic Number Here: 20

Mass # = P + N

Subtract to get # of Neutrons

21

Page 13: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Find the # of Protons and # of Neutrons in Each of the Following Isotopes:

Isotope Mass # Atomic # # of Protons

# of Neutrons

54Fe

56Mn

237Np

12C

Page 14: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Now try the other way!Isotope Mass # Atomic # # of

Protons# of

Neutrons

55 78

Page 15: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Radioactive Isotopes

-Isotopes that have unstable nuclei-They “fall apart” giving off radiation

Page 16: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Cobalt – 60 or 60Co -Is used to kill cancer cells in radiation therapy

Page 17: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Uranium-235 or 235U is used to make atomic bombs!

Page 18: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Radiation from atomic bombs can cause severe radiation burns to the skin!

Page 19: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Hydrogen-2 or 2H is called deuterium.

Deuterium oxide 2H2O is also called “Heavy Water”

It is used in Canadian (CANDU) nuclear power plants.

Page 20: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Lithium on Earth is about 7% 6Li and 93% 7Li.

Total Mass of 6Li= 7 x 6 = 42

7 7 7 7 6 7 7 7 7 7

7 7 7 7 7 7 7 7 7 7

7 7 7 7 7 7 7 7 7 7

7 7 6 7 7 7 7 7 7 7

7 7 7 7 7 7 6 7 7 7

7 7 7 7 6 7 7 7 7 7

7 7 7 7 7 7 7 7 7 7

7 7 7 7 7 7 7 7 6 7

7 7 6 7 7 7 7 7 7 7

7 7 7 7 7 7 6 7 7 7

Total Mass of 7Li= 93 x 7 = 651

Total Mass of 100 Lithium Atoms= 42 + 651 = 693

Average Mass of 1 Li Atom = 693/100 = 6.93

Page 21: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

The “weighted average” mass of isotopes of an element is called it’s Atomic Mass

Page 22: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

The “weighted average” mass of isotopes of an element is called it’s Atomic Mass

It is shown underneath the symbol on the Periodic Table

Page 23: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Element

Atomic Number

Number of Protons Atomic Mass

Ag

Se

Bh

Page 24: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

In a Neutral Atom of an Element:

The # of Electrons(-) = The # of Protons(+)

Page 25: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

In a Neutral Atom of an Element:

The # of Electrons(-) = The # of Protons(+)

Neutral Carbon has ____ Protons

Page 26: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

When white light is shone through a prism, it is separated into different colours.

Page 27: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

The Pattern of Colours is called a SPECTRUM

Page 28: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

If a single element is subjected to a high voltage, it has a spectrum too, but it is different!

Page 29: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

If a single element is subjected to a high voltage, it has a spectrum too, but it is different!

The spectrum of Hydrogen only has a few “lines”

Page 30: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Niels Bohr

A Danish Physicist

Page 31: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Bohr said the atom has different “Energy Levels” or “Orbits” or “Shells” which the electrons could inhabit.

Page 32: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

When energy is added to an atom, the electron “jumps” to a higher orbit (the atom is then in an “excited state”)

Page 33: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

When electrons jump from higher orbits back to lower orbits, they “give off” energy in the form of light.

Different “jumps” give different colours.

Page 34: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Since atoms of different elements have different electron arrangements, each element has its own unique spectrum!

Page 35: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Spectra can be used to “identify” an unknown element – like a fingerprint!

Page 36: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Bohr’s Orbits

First Orbit

Second Orbit

Third Orbit

Maximum # of

Electrons

Page 37: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Bohr Models:

Element

Atomic Number

Total # of Electrons

Electrons in First Orbit

Electrons in Second

Orbit

Electrons in Third

Orbit

He

Page 38: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Bohr Models:

Element

Atomic Number

Total # of Electrons

Electrons in First Orbit

Electrons in Second

Orbit

Electrons in Third

Orbit

C

Page 39: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Bohr Models:

Element

Atomic Number

Total # of Electrons

Electrons in First Orbit

Electrons in Second

Orbit

Electrons in Third

Orbit

N

Page 40: The Modern Theory of Atomic Structure. Atoms can be broken down into smaller particles. This was first done with a Crooke’s Tube

Bohr Models:

Element

Atomic Number

Total # of Electrons

Electrons in First Orbit

Electrons in Second

Orbit

Electrons in Third

Orbit

Cl