Chemistry: The Periodic Table

What is Chemistry?

• The study of the composition, structure, properties, and interactions of matter.

  • (What its made out of, what its shaped like, what it does, and how it reacts to different conditions)

What is Matter?

• Matter is anything that has mass and takes up space

  • Mass + Volume

• All matter is made of atoms 

  • They are the smallest unit of matter

  • Atoms are comprised of protons, neutrons, and electrons

  • Very, very small

    • Around 5 million million Hydrogen atoms can fit on the head of a pin!

Parts of the Atom

• subatomic particles that make up an atom

  • Electrons have a negative charge (-)

  • Protons have a positive charge (+) 

  • And neutrons have a neutral charge (no charge)

• In an atom, there are two main parts: the nucleus and the electron cloud

  • The nucleus sits in the center of the atom, and the electrons move around it. 

    • The nucleus is made up of protons and neutrons

    • The electron cloud looks like a cloud floating around the nucleus, much different from most renditions of the atom

The Periodic Table of Elements

• An organized table of all elements 

• Each element has an abbreviated name called a chemical symbol

  • ex.) Hydrogen’s chemical symbol is “H”; Aluminum’s chemical symbol is “Al”

• Sorted by increasing atomic number from left to right 

  • Atomic number is how many protons are in the nucleus of the atom

    • ex.) Hydrogen has 1 proton in its nucleus; Helium has 2 protons

  • Sits on the top right of the element name

• Most tables also show the atomic mass

  • Weight of all the isotopes of an element averaged together

  • Sits below the element name

• Separated into different sections

  • Metals

    • On the left and bottom

  • Non-metals

    • On the right (*with the exception of Hydrogen)

  • Metalloids

    • Separates the metals and nonmetals

• Also sorted into columns (that’s why it’s not just a rectangular block :D)

  • These columns are also known as families and that is because the elements in a family share lots of the same properties

As you can see, H, Li, Na, K, Rb, Cs,  and Fr are in the same column, aka family, and this family is called the Alkali family

• They are known for being very reactive 

Likewise, Be, Mg, Ca, Sr, Ba, and Ra are in the same family too.

This family is called the Alkali Earth family.