32
Models of Atomic Structure

Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Embed Size (px)

Citation preview

Page 1: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Models of Atomic Structure

Page 2: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres
Page 3: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Dalton Model• Unbreakable neutrally

charged spheres.

Page 4: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Thomson’s Cathode Ray Experiment• Cathode rays originate

from neutrally charged atoms.

• Cathode rays have a negative charge and are deflected by electrical charges and magnetic fields.

• Cathode rays are electrons.

Cathode Ray Tube

Page 5: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Cathode Rays = Electrons

Page 6: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Cathode Rays = Electrons

Page 7: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Cathode Rays = Electrons

Page 8: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Plum Pudding Model• Negative electrons stuck

inside and on the surface of a positive pudding.

• Atom’s mass and positive charge is widely spread.

• Electrons might wander but mostly motionless unless kicked out by a lot of energy.

• Chocolate chips in ice cream.

Page 9: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Plum Pudding Model• Negative electrons stuck

inside and on the surface of a positive pudding.

• Atom’s mass and positive charge is widely spread.

• Electrons might wander but mostly motionless unless kicked out by a lot of energy.

• Chocolate chips in ice cream.

Page 10: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Rutherford’s Gold Foil Experiment – Predicted Results

Page 11: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Rutherford’s Gold Foil Experiment – Predicted Results

Page 12: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Rutherford’s Gold Foil Experiment – Actual Results

Page 13: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Actual Results

Page 14: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Rutherford’s Gold Foil Experiment• Most alpha particles

(42He) passed right

through the gold foil. • A few alpha particles

had very large deflections.

• The Plum Pudding model would predict only small deflections.

• The mass and positive charge of an atom is concentrated in a very small nucleus.

Page 15: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Rutherford-Bohr Model• Nucleus takes up very

little space. • Electrons jump up to a

higher energy level when they absorb energy.

• Electrons falls down to a lower energy level when they emit energy.

• Electrons orbit in regular “planet-like” energy levels around the positive nucleus.

Page 16: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Rutherford-Bohr Model• Nucleus takes up very

little space. • Electrons jump up to a

higher energy level when they absorb energy.

• Electrons fall down to a lower energy level when they emit energy.

• Electrons orbit in regular “planet-like” energy levels around the positive nucleus.

Page 17: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Quantum Model• Electron clouds not

orbits. • Electrons are not found

in fixed locations, but rather probabilities to be in a location.

Page 18: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

s-orbitals

Page 19: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

p-orbitals

Page 20: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Atomic ModelsAtomic Model Description

Dalton Solid, neutrally charged spheres.

Plum-Pudding Negatively charged electrons in a glob of positive charge. Like chocolate chips in vanilla ice cream.

Rutherford-Bohr

Negatively charged electrons orbit a positive nucleus. Like planets around the sun.

Quantum Electrons are in layers of clouds around the nucleus.

Page 21: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Key11NaSodium22.99

Atomic Number•Number of Protons•Number of Electrons (when atom is neutrally charged)

•Property unique to each element

Page 22: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Key

Average atomic mass*•Weighted Average number of Protons and Neutrons (approximately)

NaSodium22.99

11

Page 23: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Subatomic Particlesthe particles that make up an atom

• Protons – high mass, positive charge. Found in nucleus.

• Neutrons – high mass, no charge. Found in nucleus.

• Electrons – low mass, negative charge. Found orbiting around nucleus. (abbreviated e– )

Page 24: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Basic Electrical Charge Laws

+ and – : Attract(pull

together)

– and – : Repel(push away)

+ and + : Repel(push

away) Like charges repel and Opposites attract

Page 25: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

An Atom

Nucleus

1 proton = H = hydrogen

Page 26: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Why doesn’t the electron fall into the nucleus?• It orbits because the electron is moving really

fast around the nucleus. • Because the electron has such a low mass,

even a small amount of energy makes it move very fast.

Page 27: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

An Atom

Nucleus

1 proton = H = hydrogen

Page 28: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Another AtomSize of atom

Size of nucleus

2 protons = He = helium

Page 29: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres
Page 30: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

Cathode Rays = Electrons

Page 31: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

NeFONCBBe

He

Li

H

Kr

ArCl

Br

XeI

SPSiMg Al

Ca

Na

K

Page 32: Models of Atomic Structure. Dalton Model Unbreakable neutrally charged spheres

4 e– in valence shell