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 Nucleus3. 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