IPC Chpt.6

Leucippus- Greek

First originated the concept of an atom

Democritus-Greek

Leucippus' student who said all things are made of atoms

Democritus' Model

Particules with hooks model

Atom means?

Indivisible

Characteristics of a good model

1) Accurately describes the data
2) Helps simplify a complex idea.
3) Accurately predicts new data

Conceptual Model

presents a concept in physical terms, so that it can be visualized and studied

Mathematical model

is used to study energy levels in different parts of the atom

Dalton-18th Century English
School teacher

1) Law of Definite Proportions
2) Core Envelope Model

What does the Law of Definate Proportions state?

Each compound is made of the same specific elements combined in unique proportions.

What does the Core Envelope Model say?

there is a hard, solid core sphere surrounded by a heat envelope?

What is the problem with Core Envelope Model?

Heat is energy and not matter!

What is the problem with Democritus' particles with hooks?

Magnetic fields, light and sound waves are not made of atoms.

What is indirect evidence?

using data you CAN observe to constsruct a model about something you CAN'T observe

JJ Thomas-British

1) Discovered the electron
2) Plum Pudding Model

What does the plum pudding model say?

a) Electrons are like Negetively charged plums in positively charged pudding
b) + charges

What does electron mean?

Greek word for amber

What is the problem with plum model?

Later work shows that atoms contain large areas of open space?

Lenard-1903

No model
Shot electrons through metal
Showed-empty spaces in atoms

Rutherford's Model?

Proton Nucleus Model

What did the proton nuclesu model say?

1) Nucleus has dense core, filled with + protons
2) Cloud of - electrons fly around nucleus-high speed

What is the problem with Proton Nucleus Model?

Mass of nucleus is greater than mass of protons;something is missing

What did Chadwick discover?

neutrons in the nucleus

What are neutrons?

particles with NO electrical charge (same size as proton)

What is the size of a nucleus?

1/100.000 of the size of the atom

Bohr's Model?

Planetary Model

What did the planetary model state?

1) Electrons move in energy levels around nucleus
2)They circle in specific orbits

What did Heisenberg say?

We don't know where an electron is at any given time.

What is the current model and who proposed it?

Quantum model- says that there are regions where electrons are most likely found and they resemble a cloud more than orbit.
Several scientists proposed it.

What is Atomic Mass?

the mass of protons and neutrons in the atom

What is the proton (prt) mass?

1836X that of electeon

What is the neutron mass?

1839X that of the electron

How do you calculate atomic mass?

By adding mass of protons + mass of neutrons

What is an atomic number?

The # of parts in the nucleus(also the #electrons)

What is an Atomic Mass Number?

The sum of all the protons and neutrons = atomic mass number

What is Isotope Notation?

Special notation showing both the mass # and proton# of an Element

What are Isotopes?

Atoms of the same element having different numbers of neutrons

What is the emission of particles and energy waves from a disintergrating atomic nucleus called?

Nuclear Radiation

What is the emission of high energy rays and particles a nucleus called?

Radioactivity

What is the study of reactions involving atomic nuclei?

Nuclear chemistry

Who observed radioactivity?

Henry Becquerel

What did Becquerel find from his experiment?

a) particles move slightly to neg.side of field.-alpha particles
b) particles that move to pos. side of field-Electrons or beta particles
c)Gamma ray- energy wave moves straight ahead

What is a model?

an idea that describes something

What did Democritus believe?

1. That atoms were the only things that exit
2) That they have always exited
3) That they will always exist

What did Dalton believe?

1) Elements are made of atoms
2) Each element has its own type of atom
3) Atoms of different elements have different masses
4) Matter is made of combinations of atoms

What the emission of alpha particles or electrons from an unstable atomic nucleus called?

Nuclear Decay

What is the reaction that occurs when an unstable nucleus is struck with atomic particles or other nuclei?

Nuclear fission

What is the process of joining two small atomic nuclei into a larger one?

Nuclear fussion

What is reactions that occur when an atomic nucleus is struck with atomic particles or other nuclei.

Nuclear bombardment reactions