Periodic Table Of Elements

Groups Vertical columns Elements of the same group have similar properties Groups 1 - 18

Periods Horizontal rows Periods # 1 – 7 Each period begins with an element containing 1 electron in outer level and ends with an element with a full outer level of electrons

Electron Energy Levels Electrons have different amounts of energy depending on where they are located in the electron cloud Electrons in lower levels (closer to nucleus) have less energy than electrons in outer energy levels Energy increases with each level

There are 7 energy levels Each level has a number of sublevels equal to its energy level Energy level 1 has 1 sublevel Energy level 2 has 2 sublevels, etc Each sublevel contains orbitals, one orbital can hold a max of 2 electrons

Sublevels The first sublevel is s Has one orbital Holds 2 electrons

The second sublevel is p Has 3 orbitals Holds a total of 6 electrons The Third sublevel is d Has 5 orbitals, hold max 10 electrons The fourth sublevel is f Has 7 orbitals, hold a max of 14 electrons

Valence electrons Electrons in the outer energy level All atoms can hold up to 8 electrons in their outer shell H and He are the exceptions (they only have level 1s and therefore room for only 2 electrons max)

Group numbers tell the number of valence electrons for an element Elements of the same group have the same # of valence electrons

Atoms want to have a full outer shell of valence electrons Atoms will share and exchange electrons in order to obtain a full outer shell This is chemical bonding

Elements of the same group number have the same number of valence electrons so they are likely to make the same types of bonds This gives elements of the same group similar properties

The closer an atom is to having a full outer shell the more reactive it will be Atoms can obtain a full outer shell by gaining electrons, losing electrons or sharing electrons with other atoms

Ions Atoms that lose or gain electrons Helps obtain a full outer shell Atoms that lose electrons are (+) = cations Atoms that gain electrons are (-) = anions

Electron dot diagrams Also call Lewis Structures Uses dots to represent the valence electrons for an atom One dot for each valence electron (group #) Helps model bonding

Draw electron dot diagrams for the following elements: Li, C, Kr, S and Ca Which is the most reactive? Which is the least reactive?

Quiz Please give the element symbol: Barium 7. Phosphorus Mercury 8. Iron Boron 9. Xenon Argon 10. Flourine Oxygen Cadmium