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Ch. 10 - Atomic Structure. II. Electron Cloud Model (p.272-274) Orbital Energy Levels Bohr Model Diagrams. A. Orbital. Region where there is 90% probability of finding an electron. Can’t pinpoint the location of an electron. Density of dots represents degree of probability. A. Orbital.
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Ch. 10 - Atomic Structure II.Electron Cloud Model (p.272-274) Orbital Energy Levels Bohr Model Diagrams
A. Orbital • Region where there is 90% probability of finding an electron. • Can’t pinpoint the location of an electron. • Density of dots represents degree of probability.
A. Orbital • Orbitals have different shapes.
B. Energy Levels • Electrons can only exist at certain energy levels. • Low energy levels are close to the nucleus. • Each energy level (n) can hold 2n2 electrons.
Can replace with: 3p 4n p n n n p p n C. Bohr Model Diagrams • Simplified energy levels using Bohr’s idea of circular orbits. Lithium Atomic #: 3 Mass: 7 # of p: 3 # of e: 3 # of n: 4 e- e- Maximum e- Level 1 2e- Level 2 8e- Level 3 18e- Level 4 32e- e-
Valence Electrons • Valance Electrons • Number of electrons in outermost energy level • Tells how an element behaves
1A 8A 2A 3A 4A 5A 6A 7A B. Periodic Trends • Group # = # of valence e- (except He) • Ex: Ca is in group 2 so it has 2 valence e- • Families have similar reactivity. • Period # = # of energy levels
C. Bohr Model Activity • Choose a number between 1 & 18. • Find your element by the atomic number you picked. • Draw a Bohr Model diagram for your element on your marker board. • Round off the mass listed on the table and subtract the atomic # to find the # of neutrons. • Abbreviate the # of ‘p’ and ‘n’ in the nucleus. • Have a partner check your drawing. • Repeat with a new element.