How are atoms studied? Atoms are the building blocks of matter Atoms are too small in size to study easily

Who studied the atom? Studied by many scientists for centuries –Democritus (400 BC) – phrase “atomos” –Rutherford (1911) – nucleus (gold foil expt) –Moseley (1913) – X-rays to find atomic # –*Bohr (1913) – planetary model of the atom –*Schrödinger (1923) – electron cloud model

Electrons circle around the nucleus of an atom. Protons are a main part of the nucleus of an atom. Neutrons also hang out in the nucleus of an atom.

Electrons have a negative charge.  Protons have a positive charge. + Neutrons have no charge. 0

Electrons are little and have a mass of almost zero. Protons are big and have a mass of one. Neutrons are also big and have a mass of one.

What is the structure of an atom? Nucleus – center of the atom –Home of Protons and Neutrons –Proton Has a positive (+) charge Has a relative mass of 1 Determines the atomic number Found inside the nucleus

What is the structure of an atom? Neutron –Has no (0) charge –Has a relative mass of 1 –Determines the isotope »Isotopes are two of the same element with different masses because they have different amounts of neutrons –Found inside the nucleus

What is the structure of an atom? Electron –Has a negative (-) charge –Has a relative mass of 0 (zero) –Determines the ion –Found outside the nucleus Bohr model – electrons are in specific energy levels Electron cloud model – electrons are in a random cloud

What is the structure of an atom? Bohr Model “Planetary Model” Schrödinger Model “Electron Cloud Model”

How are P, N, e - related? # protons = atomic number # electrons = # protons in a neutral atom # protons + # neutrons = atomic mass

Why do atoms bond? To become stable

Difference between ionic and covalent bonds Ionic BondingCovalent Bonding 1.Makes "Compounds"1.Makes "Molecules" 2.Transfers, gives/takes electrons to be noble 2. Shares electrons to be noble 3. Made with Metals and Nonmetals 3. Made of Nonmetals 4. Positive and Negative Charges 4. Neutral 5. Weak Bond5. Strong bond 6. NaCl (Salt) is a good example 6. H 2 O, CO 2, NH 3, HCl, CH 4, etc…

A covalent bond is a chemical bond in which two or more electrons are shared by two atoms. Why should two atoms share electrons? FF + 7e - FF 8e - F F F F Lewis structure of F 2 lone pairs single covalent bond 9.4

8e - H H O ++ O HH O HHor 2e - Lewis structure of water single covalent bonds The most commonly known covalent bond, H2O. WATER!!

LETS LOOK AT THE MOLECULE Cl 2 COVALENT BONDS Cl SHARED ELECTRONS Cl

SHARED ELECTRONS ARE COUNTED WITH BOTH ATOMS Cl NOTICE 8 ELECTRONS IN EACH VALENCE SHELL!!!

HOW ABOUT THE MOLECULE HCl? COVALENT BONDS Cl SHARED, BUT NOT EVENLY H Cl H

AN IMPERFECT ATOM 1 E - ON OUTER RING I WANT TO BE PERFECT!

WHAT DOES SODIUM NEED TO DO TO BECOME LIKE NEON? IT COULD LOSE AN ELECTRON! -

WHAT DOES SODIUM NEED TO DO TO BECOME LIKE NEON?

NOW SODIUM IS MORE STABLE! WHAT DOES SODIUM NEED TO DO TO BECOME LIKE NEON?

ANOTHER IMPERFECT ATOM 7 E’S ON OUTER RING I WANT TO BE PERFECT!

WHAT DOES CHLORINE NEED TO DO TO BECOME LIKE A NOBLE GAS, LIKE ARGON? IT COULD GAIN AN ELECTRON!

- WHAT DOES CHLORINE NEED TO DO TO BECOME LIKE A NOBLE GAS, LIKE ARGON? IT COULD GAIN AN ELECTRON!

WHAT DOES CHLORINE NEED TO DO TO BECOME LIKE ARGON?

SO WHAT’S THE BOTTOM LINE? AN ATOM WILL LOSE OR GAIN ENOUGH ELECTRONS TO ANOTHER ATOM IN ORDER TO BECOME STABLE.

AN ELECTRON IS TRANSFERRED FROM THE SODIUM ATOM TO THE CHLORINE ATOM

BOTH ATOMS ARE HAPPY, THEY BOTH ARE STABLE. THIS IS AN IONIC COMPOUND NOTICE 8 ELECTRONS IN EACH VALENCE SHELL!!!