Atoms, Elements, and the Periodic Table

The smallest particle in which an element can be divided and still be the same substance.

A pure substance that can't be broken down into simpler substances.

Protons- In the nucleus
Neutrons- In the nucleus
Electrons- In the cloud around the nucleus.

Protons- Positive charge
Neutrons- Neutral charge
Electrons- Negative charge

The number of protons in the nucleus.

Protons- On a periodic table, look at the element's atomic number.
Neutrons- Subtract the number of protons from the element's atomic mass
Electrons- Since electrons have negative charge, the number of electrons will be the same number as the protons. (EXCEPT for ions)

Na Cl - 1 Na atom and 1 Cl atom
Na2 HCO3 - 2 Na atoms and 3 HCO atoms
3Na2 Cl2 - 3 Molecules, 6 Na atoms and 6 Cl atoms

Challenge: 2C12H22O11 - 2 Molecules, 24 Na atoms, 44 H atoms, and 22 O atoms.

Remember: When you have a molecule, you multiply it by the number of atoms to get the real number of atoms. (See the challenge)

An atom with an electron added or subtracted. (An atom with a greater number of electrons)

An atom that has the same number of protons, but a different number of electrons.

The SI unit used to express the masses of particles in atoms.

The weighed average of the masses of all the naturally occurring isotopes of an element.

Rows- Periods - The physical and chemical properties of elements change gradually from those of a metal to those of a nonmetal.
Columns- Groups - They have the same chemical and physical properties

Add or subtract a proton: A new element
Add another atom: A molecule
Add or subtract a neutron: An isotope
Add or subtract an electron: An ion