Atoms Smallest building block of matter

Atomic Structure

Nucleus is on the insideElectron Cloud is on the outside

Atomic nucleus• Center of the atom• Mass of the atom=protons + neutrons• Dense and tightly packed

Protons

• Positive Charge• 1 atomic mass unit

Neutrons

• Neutral charge• 1 atomic mass unit

Electrons

• Negative charge• Same number as protons so that atom is

neutral.• Mass is so small, it is not counted.• Carbon has 6 protons, how many electrons?• Neon has 10 protons, how many electrons?• Argon has 18 protons, how many electrons?

Energy levels, shells

• Outside of the nucleus• Electrons move around very quickly in certain

shells or energy levels. • Mostly empty spacebecause electrons are so small.• Electrons in energy levels that are farther away from the nucleus have more energy.

Energy Levels hold electrons

• The energy levels have numbers 1,2,3,4.. • The first level holds two electrons the second

8, the next 18 and then all energy levels after that hold a maximum of 32.

• The last energy level will never have more than 8 electrons.

Electron models

• There are different models that represent how electrons move around the nucleus.

Opposites attract, likes repel• http://www.middleschoolchemistry.com/multimedia/chapter4/lesson1 - protons_

and_electrons

• This holds the atom together• http://www.middleschoolchemistry.com/multimedia/chapter4/lesson1#hydrogen

_atom

Atomic Number•The number of protons in an atom.•Each kind of atom has a different atomic number.

Atomic Mass

• Protons + Neutrons• There are differentatoms with differentatomic masses and numbersof neutrons. These are Isotopes.• The atomic mass is an average of all the isotopes of a certain element.

Calculating neutrons

• Atomic mass-atomic number= number of neutrons

• Atomic mass-number of protons =Number of neutrons

What are the number of protons, electrons and neutrons for…

What is the atomic mass and atomic number for….

• Strontium? It has 38 protons and 50 neutrons.

What is the atomic number and mass for Neon?

• Neon

Review so far:

• Name each part of the atom, its charge, location and mass.

• What does the atomic number tell you? • What does the atomic mass tell you? • How do you figure out the number of

neutrons?

What are the number of protons, electrons and neutrons for:

• Argon, atomic # 18, mass; 39.948• Bromine; atomic #35, mass: 79.904• Germanium: atomic #32; mass: 72.61

Elements

• Elements are made of one kind of atom (H, O, S)• Their symbol is a capital letter (C for Carbon) or a

capital and lower case (Fe for Iron)• How many elements are in:

FeSCOHMg

Which of these are compounds?

Compounds

• They are made of more than one element, chemically bonded.

• Bonds occur when electrons are shared or donated between two atoms.

• Their formulas are the symbols for the elements with a subscript. H2O CO2

• The smallest part of a compound is a molecule

How many atoms of each element are in:

• C6H12O6

• CH4

• Fe2O3

Make a concept map of the words:

ElementCompoundMolecule

Atom

Models

• Scientists developed theories for the structure of an atom, before they could see it.

• They developed models. Which model do tyou think was developed first?

You can make a model!

1) Move around the black disc.2) Draw a picture of what you think the shape

is.

History of ideas about the atom

• Ancient Greeks believed the first elements were Fire, water, earth and air.

• Dalton theorized that atoms were solid spheres.• The electron was discovered.• The proton was discovered.• Electrons were scattered about the atoms.• Rutherford discovered the nucleus was on the inside and electrons were on the outside.

http://reich-chemistry.wikispaces.com/file/view/Rutherford_gold-foil_experiment.jpg/146838757/Rutherford_gold-foil_experiment.jpg

Pictures of atomsThis is an image of two gold atoms. This picture was taken with an electron microscope

Pictures of atomsThis is a topographic map of a silicon atom

Pictures of atomsSilicon atoms on a surface. This picture was taken with a tunneling microscope.

How does this relate to something fun?

• http://pbskids.org/dragonflytv/show/hockeysticks.html

• NBC learns : a microscope’s image of a molecule

• https://archives.nbclearn.com/portal/site/k-12/collectionnavigator?cuecard=46384