Atomic

The atomic structure ↓

-Nucleus

-Proton

-Neutron

-Electron

-Energy levels

Nucleus

♢ The center of an atom

♢ contains protons and neutrons

♢ makes up the majority of the atoms mass

Protons

♢ Positively charged

♢ Found in the Nucleus

ATOMS: number of Protons is equal to the number of Electrons

Neutrons

♢ Neutral (n。）

♢ found in the nucleus

♢ Have about the same mass as a proton

Electrons

♢ Negatively charged

♢ Orbit around the nucleus

♢ Much smaller than protons and neutrons

Atomic models

♢ The nucleus is orbited by electrons which are in different energy levels

♢ An atom is mostly empty space

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Atomic symbols

♢ Each element has its own name. Accompanied by a symbol

♢ 1/or 2 Letters (first letter is always capitalized)

Ex: Iron Fe

♢ Fe represents one atom of iron

♢ 2Fe represents two atoms of iron

♢ 2 atoms of iron can also be written like Fe2 (H2O)

Atomic numbers

♢ Number of Protons in the Nucleus

♢ Located at the Top of the square

♢ Elements are classified by this this number

●Tell us the identify of this element

♢ Arrangements of elements by their Atomic numbers makes up the Periodic table

Atomic Mass

♢ an average or “weighted” mass

♢ Listed in amu (atomic mass units)

♢ 1 AMU = mass of proton

How do we use Atomic Mass?

♢ Round the atomic mass to a whole number to calculate the number of neutrons in an atom.

♢ Number of protons and neutrons in the nucleus

Mass number

♢ Total number of protons and neutrons in the nucleus of an atom

♢ Mass Number—Atomic number= Number of Neutrons

Isotopes

♢ atoms with the same number of protons but different numbers of neutrons

♢ Molecules-two or more atoms chemically combined

Atoms can be of different elements or the same element bonded to itself : NaCl or O2

♢ Compounds-two or more elements chemically combined.

NaCl, H2O, CO2