Biology and Organization Quiz

Atoms

This link will take you to the Khan academy page that has all of the Chemistry of Life Videos. These are only optional but if you want a more in depth explanation of chemistry you can go through these videos.

All the Videos on The Chemistry of Life

Class discussion: (In Classroom)

Turn to a partner and discuss what the word Atom means to you. What is an atom? Is everything really made up of atoms or are there some things that are not made of atoms?

There are three subatomic particles

-Neutron

-Protron

-Electron

-Protons have a positive (+) charge

-Neutrons have no charge

-Electrons have a negative (-) charge

The number of protons is what makes an element

-Atomic Number - how many protons the element has

-Atomic Mass - how many protons + neutrons the element has

-If you subtract the atomic number from the atomic mass you will know how many neutrons the element has

The periodic table is organized by atomic number

You can change an element's number of electrons and number of neutrons but you cant change its number of protons. If you change the number of protons you change the element.

-Isotope - different number of neutrons than protons

-Ion - different number of electrons than protons

-Ions have a charge. If they have more electrons than protons then they are negatively (-) charged. If they have less electrons than protons then they are positively (+) charged.

Electron Shell

-The first shell holds 2 electrons

-The second shell holds 8 electrons

-All atoms want to have a full outer electron shell. The last shell of an atom is called the valence electron shell and all electrons in that shell are called valence electrons

-The amount of valence electrons an atom has determines its properties and how it reacts

-The noble gases all have full valence electron shells so they do not react with anything

-Some elements will try to take electrons or get rid of electrons to fill its shell

-If an atom has less than 4 valence electrons it is easier to just get rid of them and drop down to its other shell making it a positive (+) ion

-If an atom has more than 4 valence electrons it will try to take electrons to get to 8 to become a negative (-) ion