Ch 4 Atomic Structure I Structure of the

A. Dalton’s Atomic Theory ¨ Every element is made of tiny, unique, particles called

B. Subatomic Particles ATOM NUCLEUS ELECTRONS PROTONS NEUTRONS POSITIVE CHARGE NEUTRAL CHARGE Most of

B. Subatomic Particles Element Symbol Element Name 10 Ne Neon 20. 179 Atomic Number

B. Subatomic Particles ¨Atoms have no overall charge because the protons (+) cancel out

Ch. 4 - Atomic Structure II. Electron Cloud Model ¨ Orbital ¨ Energy Levels

B. Energy Levels ¨ Electrons can only exist at certain energy levels. ¨ Low

A. Orbital ¨ Region where there is 90% probability of finding an electron. ¨

C. Bohr Model Diagrams ¨ Simplified energy levels using Bohr’s idea of circular orbits.

C. Bohr Model Activity ¨ Choose a number between 1 & 18. ¨ Find

Ch. 4 - Atomic Structure III. Masses of Atoms ¨ Atomic Mass ¨ Mass

A. Atomic Mass ¨ atomic mass unit (amu) – unit of measurement ¨ Average

B. Mass Number ¨ Sum of the protons and neutrons in the nucleus of

C. Isotopes ¨ Atoms of the same element with different numbers of neutrons. ¨

C. Isotopes © Addison-Wesley Publishing Company, Inc.

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Ch. 4 - Atomic Structure I. Structure of the Atom ¨ Dalton’s Atomic Theory ¨ Subatomic Particles

A. Dalton’s Atomic Theory ¨ Every element is made of tiny, unique, particles called atoms that cannot be subdivided. ¨ Atoms of the same element are exactly alike. ¨ Atoms of different elements can join to form molecules.

B. Subatomic Particles ATOM NUCLEUS ELECTRONS PROTONS NEUTRONS POSITIVE CHARGE NEUTRAL CHARGE Most of the atom’s mass. NEGATIVE CHARGE in a neutral atom Atomic Number equals the # of. . .

B. Subatomic Particles Element Symbol Element Name 10 Ne Neon 20. 179 Atomic Number = # of Protons & Electrons Atomic Mass = # of Protons + # of Neutrons

B. Subatomic Particles ¨Atoms have no overall charge because the protons (+) cancel out the electrons (-). Neon 10 protons = +10 10 neutrons = 0 10 electrons = -10 total charge 0

Ch. 4 - Atomic Structure II. Electron Cloud Model ¨ Orbital ¨ Energy Levels ¨ Bohr Model Diagrams

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 a certain number of electrons.

A. Orbital ¨ Region where there is 90% probability of finding an electron. ¨ Can’t pinpoint the location of an electron. ¨ Density of dots represents the probability.

C. Bohr Model Diagrams ¨ Simplified energy levels using Bohr’s idea of circular orbits. Lithium Atomic #: 3 Mass: 7 # of p: # of e: # of n: 3 3 4 een np n pn p e- Can replace with: 3 p 4 n Maximum e. Level 1 Level 2 Level 3 Level 4 2 e 8 e 18 e 32 e-

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 atomic 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.

Ch. 4 - Atomic Structure III. Masses of Atoms ¨ Atomic Mass ¨ Mass Number ¨ Isotopes

A. Atomic Mass ¨ atomic mass unit (amu) – unit of measurement ¨ Average atomic mass – the average mass of all the isotopes of the atom. © Addison-Wesley Publishing Company, Inc.

B. Mass Number ¨ Sum of the protons and neutrons in the nucleus of an atom. ¨ Always a whole number. © Addison-Wesley Publishing Company, Inc. ¨ # of neutrons = mass # - atomic #

C. Isotopes ¨ Atoms of the same element with different numbers of neutrons. ¨ Isotope symbol: Mass # Atomic # “Carbon-12”