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- Matter was thought to be made from tiny indestructible building blocks
- First proposed in early 1800's by John Dalton.
Dalton's Atomic Theory
The atom is the basic unit from which matter is constructed.
Protons, Neutrons and Electrons which make up the atom.
The compact core of an atom made up of Proton and Neutrons.
- Mass of 1.6726 x 10-*24 G
- Mass of 1.0073 AMU
- Location in Nucleus
- Same number of electrons
- Property is to attract electrons closer
- Mass of 1.6750 x 10-*24
- Mass of 1.0087 AMU
- Location in Necleus
- Mass of 9.110 x-*28
- Mass of 5.486 x 10-*4 AMU
- Location outside of Nucleus
- Same number of Protons
A substance that contains only one type of atom.
A one or two letter abbreviation of the element name
- The number of protons that an atom has in its nucleus
- Also same number of electrons
The total number of Protons and Neutrons in the nucleus of an atom
- To specify the number of Protons and Neutrons in the nucleus of a particular atom
- Atoms of an element that have different numbers of Neutrons
- All elements have more than one isotope and the isotopes of an element are usually not present in nature in equal amounts.
- The average mass of the atoms of an element, as it is found in nature.
- ~50% 79/35Br (mass=78.92 amu) and ~50% 81/35Br (mass=80.92 amu).
- The Atomic Weight is 79.91 amu, which falls in between
- Located under Atomic Symbol of Table
Elements in the same vertical column of the periodic table belong to the same group
Group - Alkali Metals
- H? - Li - Na - K - Rb - Cs
- Hydrogen? - Lithium - Sodium - Potassium - Rubidium - Cesium
Group - Alkaline Earth Metals
- Be - Mg - Ca - Sr - Ba - Ra
- Beryllium - Magnesium - Calcium - Strontium - Barium - Radium
Group - Halogens
- F - Cl - Br - I - At
- Florine - Chlorine - Bromine - Iodine - Astatine
Group - Inert or Noble Gases
- He - Ne - Ar - Kr - Xe - Rn
- Helium - Neon - Argon - Krypton - Xenon - Radon
Groups 1A - 8A (Main Group)
Transition Metals (Elements)
Groups 1B - 8B
Atomic Numbers of 58 - 71
Atomic Numbers of 90 - 103
- Elements in the same horizontal row of the Periodic Table
- "Period" relates to the periodic (regular) changes that take place in the properties of elements as you move through them in order of atomic number
- H and He make up the frist period
- Li, Be, B, C, N, O, F, and Ne are the second period
- When metals, semi-metals and nonmetals change in the same period
- In 3rd period - Na, Mg, and Al are metals then moving to Si which is semi-metal then to P, S, Cl, and Ar which are Nonmetals.
- Generally decreases when moving left to right from a period
- Increase when moving down a group
- More Protons means electrons are attracted closer to the center, decreasing in size
- Going down, we begin getting more shells of electrons, increasing in size.
- Used when a very large number of atom are involved in experiments
- One mole of something contains 6.02 x 10*23 items
- 6.02 x 10*23
- Is equal to the number of atoms in exactly 12 grams of pure carbon-12
- 12.01 g C
- The mass (in grams) of one mole of the atoms of an element
- Numerically equal to the atomic weight of the elements (in amu).
- Example - AW of Li is 6.94 amu and MolMass of Li is 6.94 g/mol.
- Most stable electron arrangement
- When electrons are in energy levels as near as possible to the nucleus
- An orbit farther from the nucleus
- When ground state hydrogen atom absorbs energy it's electrons is pushed to
Type of energy that travels as waves
Metals and Non-metals and Chemical Property
- Metals - Lose an electron during chemical property
- Nonmetals - Gain electron during chemical property
Row of elements: Periods
- 1: 2 elements
- 2 and 3: 8 elements each
- 4 and 5: 18 elements each
- 6: 32 : 18 + 14 (Lanthanide)
- 7: Incomplete
Electron Dot Structure
Shows the number of valence electrons a atom carries
What group of elements cannot lose or gain electrons?
Inert Gases - 8A - very stable and lazy
Substance that contains only one type of atom