Atoms and the Atoms and the Periodic Table Periodic Table Chapter 8 Chapter 8
Dec 22, 2015
Homework AssignmentHomework AssignmentChap 8Chap 8
Read p 223 – 231; 236 - 242Read p 223 – 231; 236 - 242
Applying the Concepts (p 243): 1 – 13, Applying the Concepts (p 243): 1 – 13,
15 – 17, 19, 23 - 35, 39 – 44, 46 - 5015 – 17, 19, 23 - 35, 39 – 44, 46 - 50
Dalton’s Atomic Theory (1808)Dalton’s Atomic Theory (1808)(Listed on p 224)(Listed on p 224)
1.1. ElementsElements are composed of extremely small particles are composed of extremely small particles called called atomsatoms. .
2.2. All atoms of a given element are identical, having the All atoms of a given element are identical, having the same size, mass and chemical properties. same size, mass and chemical properties.
3.3. The atoms of one element are different from the atoms of The atoms of one element are different from the atoms of all other elements.all other elements.
4. 4. CompoundsCompounds are composed of atoms of more than one are composed of atoms of more than one element. The relative number of atoms of each element in element. The relative number of atoms of each element in a given compound is always the same.a given compound is always the same.
5. Chemical reactions only involve the rearrangement of atoms. 5. Chemical reactions only involve the rearrangement of atoms. Atoms are not created or destroyed in chemical reactions. Atoms are not created or destroyed in chemical reactions.
1. Atom’s positive charge is concentrated in the nucleus2. Proton (p) has opposite (+) charge of electron (-)
(1908 Nobel Prize in Chemistry)
Fig 8.5 Fig 8.6
atomic radius ~ 1 x 10-10 m
nuclear radius ~ 5 x 10-15 m
Planetary Model of the Atom
“If the atom is the Houston Astrodome, then the nucleus is a marble on the 50-yard line.”
Empty space!
Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Isotopes - atoms of the same element (X) with different numbers of neutrons in their nuclei
XAZ
H11 H (D)2
1 H (T)31
U23592 U238
92
Mass Number
Atomic NumberElement Symbol
0.72% natural abundance
6 protons, 8 (14 - 6) neutrons, 6 electrons
38 protons, 46 (84 - 38) neutrons, 38 electrons
Do You Understand Isotopes?
How many protons, neutrons, and electrons are in C14
6 ?
How many protons, neutrons, and electrons are in Sr 84
38 ?
Visible light consists of electromagnetic waves
Electromagnetic radiation: emission and transmission of energy in the form of electromagnetic waves.
Speed of light (c) in vacuum = 3.00 x 108 m/s
Fig. 7.2
White light is separated into its color
components by a diffraction grating
The tracks of a compact disc act as a diffraction grating,producing a separation of the colors of white light.
1. e- can only have specific (quantized) energy values
2. light is emitted as e- moves from one energy level to a lower energy level
Bohr’s Model of the Atom (1913)
n (principal quantum number) = 1,2,3,…
Fig 8.10
e-
Metals
• good conductors of heat and electricity
• shiny, ductile, malleable
• all solids with one exception
Nonmetals
• poor conductors
• dull appearance, brittle
• consist of solids, liquids, and gases
Physical Properties of the ElementsPhysical Properties of the Elements