Horizontal rows are called periods
– There are 7 periods Vertical columns are called groups
– There are 18 groups
Atoms are made of 3 particles
– Protons: + charge
– Neutrons: no charge
– Electrons: – charge
Protons & neutrons are in nucleus
Electrons in cloud surrounding nucleus
Each element has a symbol
The number on top is the number of protons (atomic number)
The name is beneath the symbol
The atomic mass is the total amount of protons and neutrons
Atoms with unfilled shells have a strong tendency to lose/ gain electrons
Atoms of the same element that differ in their number of neutrons are isotopes
Move across periodic table left to right
-Sizes of the atoms decrease
– More protons create a stronger pull on electrons
- Atoms become more electronegative
– Ability to attract another electron becomes stronger
- Atomic number and mass increases
– Each successive atom has one more electron, neutron and proton
- Atoms become less metallic
Electron Shells Hydrogen
1st shell- 2 electrons - 1 proton
2nd shell- 8 electrons - 0 neutrons
3rd shell- 8 electrons - 1 electron
As you move down a group
-Atoms increase in size and mass
-Add more neutrons, protons, and electrons
- Atoms become more reactive
• Hydrogen belongs to a family of its own.
• Hydrogen is a diatomic, reactive gas.
• Hydrogen was involved in the explosion of the Hindenberg.
• Hydrogen is promising as an alternative fuel source for automobiles
• 1st column on the periodic table (Group 1) not including hydrogen.
• Very reactive metals, always combined with something else in nature (like in salt).
• Soft enough to cut with a butter knife
Alkaline Earth Metals
• Second column on the periodic table. (Group2)
• Reactive metals that are always combined with nonmetals in nature.
• Several of these elements are important mineral nutrients (such as Mg and Ca
• Elements in groups 3-12
• Less reactive harder metals
• Includes metals used in jewelry and construction.
• Metals used “as metal.”
• Elements in group 13
• Aluminum metal was once rare and expensive, not a