Atomic Structure

What is an atom? An atom is the smallest part of matter that keeps unique properties. Ex: Iron The charge on an atom is ALWAYS ZERO!!!!!

Subatomic Particles Atoms are made of three smaller parts Protons Neutrons Electrons

H Protons Where: In the Nucleus Relative mass: 1 AMU Charge: Positive + Atomic Number = the number of protons All the atoms of an element have the same number of protons. Hydrogen 1 H 1.0079

Atomic Number Practice What’s the atomic number for lithium? What’s the atomic number for nitrogen? What’s the atomic number for zinc? What’s the atomic number for chlorine?

Neutrons Where: In the nucleus Relative mass: 1 AMU Charge: 0 (No charge) The same element can have different numbers of neutrons The atomic mass – atomic number = # of neutrons

H Atomic Mass The average mass of one atom of an element. Hydrogen 1 H 1.0079 The average mass of one atom of an element. The atomic mass is equal to the number of protons + the number of neutrons.

Atomic Mass Practice Find the atomic mass of each of the following elements Argon Tin Calcium Yttrium

Finding the Number of Neutrons Atomic Mass – Atomic Number = # of Neutrons

Electrons Where: Outside the nucleus in orbitals Relative mass: 1/2000 AMU Charge: Negative (-) The number of electrons cause the chemical properties of an atom

Electrons: Atoms of the same element can have different numbers of electrons. The atomic number is equal the number of electrons in an atom.

Electron Practice How many electrons are in a atom of nitrogen? How many electrons are in an atom of chromium?

Shape of an Atom An atom has a tightly packed nucleus containing protons and neutrons. The electrons are located in an orbital outside of the nucleus.