Atoms and the Periodic TableAtoms and the Periodic Table

Chapter 17Chapter 17

ObjectivesAt the end of this lesson, you should be able to:

Describe and define atoms and their subatomic particles

Describe the relationship between atoms and elements

Describe how atoms are held together

17.1-Elements contain a single kind of atom

Atoms make up all of the matter around you.

To date, there about 120 known distinct atoms

about 90 are found in nature

17.1-Elements contain a single kind of atom

Element - any material made of only 1 type of atom (ex. gold, nitrogen)

All elements are listed in a chart called the periodic table

Each element has its own atomic symbol

What is an element?

A. A material containing 1 or more atoms.

B. A material made of only 1 type of atom.

C. A material made of 1 or more atoms chemically bonded together.

17.1-Elements contain a single kind of atom

Atoms - very, very old

Formed @ beginning of the universe

Recycled and redistributed over and over

17.1-Elements contain a single kind of atom

Atoms - very, very small

Can’t be seen w/ visible light

Smaller than wavelengths of visible light

17.1-Elements contain a single kind of atom

Atoms - made of subatomic particles - electrons, protons, and neutrons

Atoms only differ in # of these particles

p’s and n’s-bound together to form the atomic nucleus

e’s - surround nucleus in an electron shell or electron orbital

Can’t pinpoint location of e’s - just know about where they are in shells/orbitals

17.2 - Atoms are mostly empty space

e’s move around the nucleus in an atom, but are widely separated from the nucleus

∴, atoms are mostly empty space.

Which two subatomic particles can be found in the atomic nucleus?

A. Proton and electron

B. Electron and Neutron

C. Neutron and proton

17.2 - Atoms are mostly empty space

Atoms don’t pass through each other because of electrical repulsion

Like charges repel - they move away from each other

So, atoms can only get so close before they start repelling each other

17.2 - Atoms are mostly empty space

How are atoms held together?

Electrical forces - forces of attraction or repulsion

Protons have a + charge; Electrons have a - charge

Opposite charges attract each other -

The positively charged nucleus (p’s and n’s) is attracted to the negatively charged electrons, thus holding the atom together.

Atoms are held together by the electrical attraction between

A. The negatively charged nucleus and the positively charged electrons.

B. The negatively charged electrons and the neutrally charged nucleus.

C. The negatively charged electrons and the positively charged nucleus.