Chapter 4 - cp Atoms

4.1 Journal – Using Analogies “If I have the belief that I can do it, I shall acquire the capacity to do it even if I may not have it at the beginning.-Mahatma Gandhi The network of blood vessels in your body is like the network of streets and highways in a large city. How are the two networks similar? Both networks are used to transport objects from one location to another. The comparison is an example of an analogy. An analogy uses a similarity to compare two objects or systems. A familiar object is often used to help explain a less familiar object. 1. Atoms in compounds are like bricks in a wall. Explain this analogy. 2. Think of and explain another analogy for atoms in compounds. 3. WORK ON THE “ATOMIC MATH” WORKSHEET – use section 4.2 vocabulary to help you with the top section

4.2 Journal “If I have the belief that I can do it, I shall acquire the capacity to do it even if I may not have it at the beginning.-Mahatma Gandhi Take out your homework. Begin filling out the boxes on the Periodic Table Basics sheets.

Studying Atoms ANCIENT GREEKS- DEMOCRITUS: “atomos” = indivisible, uncut Different types of atoms with specific properties ARISTOTLE: Only 4 elements No limit to divisions

DALTON’S ATOMIC THEORY: all matter is made of particles that cannot be divided Evidence: Compounds have fixed compositions H2O 2g H always combines with 8g O 4g H always combines with 16g O

4.1 Studying Atoms DALTON’S ATOMIC THEORY: all matter is made of particles that cannot be divided Evidence: Chemical reactions are a rearrangement of solid atoms.

Studying Atoms DALTON’S ATOMIC THEORY:

THOMSON’S ATOMIC THEORY: all matter is made of particles that CAN be divided EVIDENCE: Particles collected on metal plate

THOMSON’S ATOMIC THEORY: all matter is made of particles that CAN be divided The particles ALWAYS had a mass 1/2000 of a Hydrogen atom. The beam was always attracted to the positive side

THOMSON’S ATOMIC THEORY: all matter is made of particles that CAN be divided CONCLUSION: These particles came from the atoms.

Thomson’s “plum pudding” Model Explained neutral atoms with charges

Studying Atoms RUTHERFORD’S ATOMIC THEORY: all atoms positive charge is concentrated in the nucleus

RUTHERFORD’S ATOMIC THEORY: all atoms positive charge is concentrated in the nucleus Discovered: Uranium emits fast moving positive particles

RUTHERFORD’S ATOMIC THEORY: all atoms positive charge is concentrated in the nucleus If you shoot these positive particles at other atoms (Thomson’s plum pudding atom), what would happen to the particle?

Studying Atoms – Gold Foil Experiment

4.1 The Gold Foil Experiment RUTHERFORD’S ATOMIC THEORY: all atoms positive charge is concentrated in the nucleus

Studying Atoms – Modern Atomic Theory Bohr Atom: Electrons are in energy levels Electrons move when they gain or lose energy (example)

4.2/4.3 The Structure of the Atom & Modern Atomic Theory JOURNAL: 1. Q UIETLY work on the “Lewis Dot Structures” Worksheet from the back table. Use the Periodic Table in your book to help you.

Parts of an ATOM: Subatomic particles – distinguished by mass, charge and location

Subatomic particle PROPERTIES Protons (p+): In the nucleus Charge of 1+ Mass of 1 DEFINES THE ELEMENT (equals the ATOMIC NUMBER)

Protons (p+): Atoms of DIFFERENT elements have DIFFERENT numbers of protons

Subatomic particle PROPERTIES Neutrons (n°): In the nucleus NO charge Mass of 1 Protons + neutrons = the ATOMIC MASS

Neutrons (n°): Atoms of the same element with DIFFERENT numbers of neutrons are called ISOTOPES

Neutrons (n°): ISOTOPES of Hydrogen. Same Atomic #, different Mass #

Electrons (e-): In ENERGY LEVELS around the nucleus Charge of 1- Mass of 1/1836 of a p+ Equal to the number of protons The outermost shell of electrons is called the VALENCE SHELL which holds the VALENCE ELECTRONS. Take out Bohr Diagram Sheet.

Electrons (e-): Change ENERGY LEVELS when the atom GAINS or LOSES energy The most stable electron arrangement

Electrons (e-): CurrentTheory – “Electron Cloud Model” (p116-17) Orbitals that show most PROBABLE location of electrons

Electrons (e-): Atoms of the same element with different number of ELECTRONS are called IONS

IONS: form to make the outermost shell stable

4.2/4.3 The Structure of the Atom & Modern Atomic Theory JOURNAL: 1. Q UIETLY take out your Periodic Table Basics. 2. S TUDY FOR YOUR VOCAB QUIZ ON YOUR OWN.