What are they and what do they do? 2/23/2019 Atoms What are they and what do they do?

What are atoms? Atoms are the smallest particles of matter Atoms make up everything around us Molecules are combinations of atoms Elements are only one type of atom Compounds are made up of different types of atoms Hydrogen Gas Water Dan Kelly - Magic of Electrons - PLTW - Atoms

Components of an Atom Nucleus. Protons: (+) Neutrons: Electrons: (-) 2/23/2019 Components of an Atom At the center of all atoms is the Nucleus. The nucleus contains protons and neutrons. Protons: (+) Positively charged atomic particles Neutrons: Uncharged (neutral) atomic particles Orbiting around the nucleus are the electrons. Electrons: (-) Negatively charged atomic Particles Demonstration on positive vs. negative Dan Kelly - Magic of Electrons - PLTW - Atoms

Periodic table Vertical columns- groups. Horizontal rows- periods. Periodic table used to be arranged in order of increasing atomic mass but they are now arranged so that vertical columns (groups) have similar properties. They also have the same number of electrons in their outer electron shell.

Helium Protons: 2 Electors: 2 Neutrons: 4.003 – 2 = 2.003 = 2

Try this one yourself.

Potassium Protons: 19 Electrons: 19 Neutrons: 39.1 – 19 = 20.1 = 20

Questions Calculate the number of protons, neutrons, and electrons for the following:

Chemical Science We know that substances are made of atoms and molecules. When an chemical change occurs, the atoms in the molecules re-arrange to form different combinations. The substances we start with are called reactants The substance we end up with are called products Reactants Products

Atomic Number Atomic Number = The number of protons And for an element the number of protons will equal the number of electrons.

Atomic Mass Atomic Mass = The number of protons + The number of neutrons If we subtract the Atomic number from the Atomic mass then we are left with just the number of Neutrons for that element. Atomic mass-Atomic number= number of neutrons