Download Chapter Three - GEOCITIES.ws

Chapter Three
Dalton’s Atomic Theory:

Every element is made of tiny, unique particles
called atoms that cannot be subdivided

Atoms of the same element are exactly alike

Atoms of different elements can join to form
molecules
Because of new technology, we have discovered
some holes in Dalton’s Atomic Theory
Breaking Down the Atom
1. Nucleus-center of an atom, all the mass
of the atom is here


it has a positive charge
made up of protons and neutrons
Breaking Down the Atom
2. Protons-a positively charged particle


It’s a subatomic particle
has an atomic mass of 1 AMU
1. Neutrons-a neutral charged particle = NO
CHARGE



Subatomic particle
same mass and size as a protons
In reality, it is basically a proton that has
neutralized its positive charge by absorbing an
electron.
To Sum up the Nucleus

The nucleus is made up of protons and
neutrons. Protons and neutrons are both
relatively the same mass and size but
protons have a positive electrical charge
and neutrons have no electrical charge.
Outside the Nucleus
1. Electron-a negative charged particle

Very small mass (.000001 AMU)

Move around the nucleus because of the
attraction btwn + and – charges

Creates a “cloud” because the electrons
are moving very fast.
Outside the Nucleus
2.Energy-level-this is a location where
electrons can be found based on their
energy.

The more energy they have, the further
away they are from the nucleus.

Electrons can only be found in certain
energy levels
Outside the Nucleus
3. Orbital-a region in an atom where there is
a high probability of finding electrons.
 Electrons
may occupy 4 distinct orbitals
within atoms.
*** Since all electrons are negatively
charged, they repel each other, therefore
they will always be as far away from each
other and still fill an electron cloud.
- Opposite Charges Attract, Like
Charges Repel
Understanding the PTE



Valence Electron- an electron in the outermost
energy level of an atom
Periodic Table of the Elements
*This is a tool used by scientists to classify
elements
*It is not to be memorized, just applied
Periodic law- properties of elements tend to
change in a regular pattern when elements are
arranged in order of increasing atomic number,
or number of protons each has.
Periodic Table of the Elements


Period- a horizontal row of elements in the
periodic table.
- 7 total rows
- each represents the number of electron
clouds in that element
Group (family)-a vertical column of elements in
the periodic table
- All elements in a family have similar
properties
- All have the same number of valence
electrons.
- All usually will bond to the same cation(s) or
anion(s)
Learning from the PTE

Ionization-the process of adding electrons or
removing electron from an atom
-Atoms that do not have filled outer electron
clouds can undergo a process called ionization.
- This process results in a more stable atom.
- Based on the position of the atom on the PTE.
Becoming Stable

Ion-an atom or group of atoms that has lost or
gained one or more electrons therefore has a
net electric charge

Cation-an ion with a positive charge
- it loses an electron
- it now will have more protons than
electrons making it positive

Anion-an ion with a negative charge
- it gains electrons
- it now has more electrons than protons
Information from the PTE

Atomic number -the number of protons in the
nucleus of an atom
- The atomic number also equals the number of
electrons it has.
- Each element has a different atomic number

Mass number -the total number of protons and
neutrons in the nucleus of an atom
- represents average of all the different atoms
of an elements
- The mass number includes only the number
of protons and neutrons because protons and
neutrons provide most of the atoms mass.
Exceptions to Daltons Rule

Isotopes-any atoms having the same number of
protons but different number of neutrons
- Most elements have at least one different isotope
- Hydrogen has three:
1.Normal- Hydrogen 1
2.Deuterium- Hydrogen 2 = 1 proton & 1 neutron
3.Tritium- Hydrogen 3 = 1 proton & 2 neutron
** this one is radioactive- glows in the dark
Finding out about the Atoms

Atomic mass unit- represents the amount
of mass of one proton of an element

Average atomic mass- the weighted
average of the masses of all naturally
occurring isotopes of an element
Elements on the PTE

Metals- the elements that are good conductors
of heat and electricity
- Most are shiny solids that can be stretched
and shaped
- are malleable- can be easily bent
- Families 1-12
- can only loses electrons to form + ions

Nonmetals- the elements that are not good
conductors of heat and electricity
- groups 13-18(approximately)
- Nonmetals may be solids, liquids, or gases.
Metals

Semiconductors- the elements that are
intermediate conductors of heat and electricity
Ex: Metalloids

Alkali metals- the highly reactive metallic
elements located in group 1 of the periodic table
Ex. H, Na, Li, K, lose 1 e- to have a full
valence shell
** most are dangerously explosive
Metals continued

Alkaline earth metals- the reactive metallic
elements located in group 2 of the periodic table
Ex. Mg, Ca- Lose 2 e-s to fill their outer
Electron cloud

Transition metals- the metallic elements
located in groups 3-12 of the periodic table
* Have overlapping electron clouds
* They are much less reactive then sodium or
calcium, but they can lose electrons to form
positive ions
**VERY IMPORTANT – they cannot gain e-s
Halogens

Halogens-the highly reactive elements
located in group 17 of the periodic table
- They gain 1 electron to have a full
electron cloud
- React very fast with group 1 metals
Ex. Cl, Fl, Br and I
Kings of the PTE
Noble gasses- the un-reactive gaseous
elements (Group 18)
* have full valence shells
* happy atoms
* Because these atoms have filled outer electron
clouds, they do not need to lose or gain
electrons to become stable.

Counting Atoms

Mole-the SI base unit that describes the amount of
substance
* Mole day 10-23

Avogadro's number- the number of particles in 1 mole
equals 6.022x 10to the 23rd /mol Particles

Molar mass- the mass in grams of 1 mole in a
substance
Conversion factor-a ratio equal to one that expresses the
same quantity in two different ways
1 mole = 6.02*10to the 23rd particles
