Transcript Chapter 4 - H - Regional School District 17

Chapter 4 cp
Atoms
4.1 Journal – Using Analogies
“If I have the belief that I can do it, I shall acquire the capacity to do it even if I may not have it
at the beginning.
-Mahatma Gandhi
The network of blood vessels in your body is like the network
of streets and highways in a large city. How are the two
networks similar? Both networks are used to transport
objects from one location to another. The comparison is an
example of an analogy. An analogy uses a similarity to
compare two objects or systems. A familiar object is often
used to help explain a less familiar object.
1. Atoms in compounds are like bricks in a wall. Explain
this analogy.
2. Think of and explain another analogy for atoms in
compounds.
3. WORK ON THE “ATOMIC MATH” WORKSHEET – use
section 4.2 vocabulary to help you with the top section
4.2 Journal
“If I have the belief that I can do it, I shall acquire the capacity to do it even if I may not have it
at the beginning.
-Mahatma Gandhi
Take out your homework.
Begin filling out the boxes on the Periodic Table
Basics sheets.
Studying Atoms
ANCIENT GREEKSDEMOCRITUS:
 “atomos” = indivisible, uncut
 Different types of atoms with specific properties
ARISTOTLE:


Only 4 elements
No limit to divisions
Studying Atoms
DALTON’S ATOMIC THEORY: all matter is made of
particles that cannot be divided
Evidence:

Compounds have fixed compositions
H2O
2g H always combines with 8g O
4g H always combines with 16g O
4.1 Studying Atoms
DALTON’S ATOMIC THEORY: all matter is made of
particles that cannot be divided
Evidence:

Chemical reactions are a rearrangement of solid
atoms.
Studying Atoms
DALTON’S ATOMIC THEORY:
Studying Atoms
THOMSON’S ATOMIC THEORY: all matter is made
of particles that CAN be divided
EVIDENCE:

Particles collected on metal plate
Studying Atoms
THOMSON’S ATOMIC THEORY: all matter is made
of particles that CAN be divided


The particles ALWAYS had a mass 1/2000 of a
Hydrogen atom.
The beam was always attracted to the positive side
Studying Atoms
THOMSON’S ATOMIC THEORY: all matter is
made of particles that CAN be divided
CONCLUSION:

These particles came from the atoms.
Thomson’s “plum pudding” Model
Explained neutral
atoms with charges
Studying Atoms
RUTHERFORD’S ATOMIC THEORY: all atoms
positive charge is concentrated in the nucleus
Studying Atoms
RUTHERFORD’S ATOMIC THEORY: all atoms
positive charge is concentrated in the nucleus
Discovered:

Uranium emits fast moving positive particles
Studying Atoms
RUTHERFORD’S ATOMIC THEORY: all atoms
positive charge is concentrated in the nucleus

If you shoot these positive particles at other atoms (Thomson’s
plum pudding atom), what would happen to the particle?
Studying Atoms – Gold Foil Experiment
4.1 The Gold Foil Experiment
RUTHERFORD’S ATOMIC THEORY: all atoms positive charge is concentrated in the nucleus
Studying Atoms – Modern Atomic Theory
Bohr Atom:
Electrons
are in energy levels
Electrons move when they gain or lose energy
(example)
4.2/4.3 The Structure of the Atom & Modern Atomic
Theory
JOURNAL:
1.
QUIETLY work on the “Lewis Dot Structures”
Worksheet from the back table. Use the Periodic Table
in your book to help you.
Parts of an ATOM:
Subatomic particles – distinguished by mass,
charge and location
Subatomic particle PROPERTIES
 Protons (p+):
In the nucleus
 Charge of 1+
 Mass of 1
 DEFINES THE ELEMENT
(equals the ATOMIC NUMBER)

Protons (p+):

Atoms of DIFFERENT elements have
DIFFERENT numbers of protons
Subatomic particle PROPERTIES
 Neutrons (n°):




In the nucleus
NO charge
Mass of 1
Protons + neutrons = the ATOMIC MASS
Neutrons (n°):

Atoms of the same element with
DIFFERENT numbers of neutrons are called
ISOTOPES

Neutrons (n°):

ISOTOPES of Hydrogen. Same Atomic #,
different Mass #
Electrons (e-):





In ENERGY LEVELS around the nucleus
Charge of 1Mass of 1/1836 of a p+
Equal to the number of protons
The outermost shell of electrons is called the
VALENCE SHELL which holds the VALENCE
ELECTRONS.
Take out Bohr Diagram Sheet.
Electrons (e-):

Change ENERGY LEVELS when the atom GAINS or
LOSES energy
The most stable
electron arrangement
Electrons (e-):

CurrentTheory – “Electron Cloud Model” (p116-17)

Orbitals that show most PROBABLE location of electrons
Electrons (e-):

Atoms of the same element with different
number of ELECTRONS are called IONS
IONS: form to make the outermost shell stable
4.2/4.3 The Structure of the Atom & Modern Atomic
Theory
JOURNAL:
1.
2.
QUIETLY take out your Periodic Table Basics.
STUDY FOR YOUR VOCAB QUIZ ON YOUR
OWN.