Atomic Structure Unit 3 Atomic Structure If a

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Atomic Structure Unit 3

Atomic Structure Unit 3

Atomic Structure • If a nucleus were the size of baseball, a baseball would

Atomic Structure • If a nucleus were the size of baseball, a baseball would be the over 3000 miles high. • Nucleus- positive center of atom – makes up 99. 9% of the atom’s mass. • Electron cloud- contains negatively charged e-. – takes up virtually the entire volume of the atom.

Atomic Particles Charge Proton Electron Neutron +1 -1 0 mass (amu) Location 1 Nucleus

Atomic Particles Charge Proton Electron Neutron +1 -1 0 mass (amu) Location 1 Nucleus 1/1836 e- cloud 1 Nucleus

Atomic Particles (Cont. ) • atomic number: # of protons. • Protons identify the

Atomic Particles (Cont. ) • atomic number: # of protons. • Protons identify the element. If the # of protons changes, the element changes. • Since all atoms are neutral, the: # of e- = # of p+

Atomic Particles (Cont. ) • Atomic Mass (mass number) = # protons + #

Atomic Particles (Cont. ) • Atomic Mass (mass number) = # protons + # neutrons. Atomic Mass Atomic # # of Neutrons 12 C 6 Atomic Mass Atomic #

Mass Number Mass number is the number of protons and neutrons in the nucleus

Mass Number Mass number is the number of protons and neutrons in the nucleus of an isotope. Mass # = p+ + n 0 Nuclide p+ n 0 e- 8 10 8 18 Arsenic - 75 33 42 33 75 Phosphorus - 31 15 16 15 31 Oxygen - 18 Mass # Courtesy of Mr. Allen, El Diamante HS, Sciencegeeks. com

Relative Atomic Mass • Masses of atoms expressed in grams are very small. •

Relative Atomic Mass • Masses of atoms expressed in grams are very small. • For this reason, we use relative mass. – The standard used by scientists to govern units of atomic mass is carbon 12 atom. It has been arbitrarily assigned a mass of exactly 12 atomic mass units (amu).

Relative Atomic Mass (Cont) • The hydrogen-1 atom has an atomic mass of about

Relative Atomic Mass (Cont) • The hydrogen-1 atom has an atomic mass of about 1/12 that of carbon-12 atom, or about 1 amu. • An oxygen-16 atom has about 16/12(or 4/3) the mass of carbon-12 atom…and so on

Isotopes • Isotopes are alternate forms of an element. They have the same number

Isotopes • Isotopes are alternate forms of an element. They have the same number of protons but different numbers of neutrons and thus, different masses. 12 C 6 Atom 14 C 6 Isotope 1 2 H H 1 1 Atom Isotope 3 H 1 Isotope

Isotopes (Cont. ) • If the atomic mass on the periodic table matches the

Isotopes (Cont. ) • If the atomic mass on the periodic table matches the mass of your example, it is an atom. If not, it is an Isotope. • Many Isotopes are radioactive forms of an element.

Isotopes

Isotopes

Let’s Practice 25 Mg 12 31 P 15 235 U 92 # protons =

Let’s Practice 25 Mg 12 31 P 15 235 U 92 # protons = 12 # electrons = # neutrons = 12 13 # protons = 15 What is it? # electrons = # neutrons = 15 16 An Atom! # protons = 92 What is it? 92 143 An Isotope! # electrons = # neutrons = What is it? An Isotope!

Ions • When the number of electrons changes, the ‘atom’ now has a charge

Ions • When the number of electrons changes, the ‘atom’ now has a charge and is called an Ion. • A Cation has more protons than electrons and is a positively charged ion: Na+1, Ca+2 • An Anion has more electrons than protons and is a negatively charged ion: O-2, Cl-1

Ions are Important Heart cell rhythm depends on the opening and closing of a

Ions are Important Heart cell rhythm depends on the opening and closing of a complex series of valves on the cell membrane, called ion channels. Some valves let certain ions ike potassium (K+) flow out, others let different ions like sodium (Na+) flow in. There also pumps that actively move ions one direction or another. Courtesy of Mr. Allen, El Diamante HS, Sciencegeeks. com

Let’s Practice 40 Ca+2 20 # protons = 20 What is it? # electrons

Let’s Practice 40 Ca+2 20 # protons = 20 What is it? # electrons = # neutrons = 18 20 A Cation! 80 Br 35 # protons = 35 What is it? # electrons = # neutrons = 36 45 # protons = 13 What is it? 10 14 A Cation! -1 27 Al+3 13 # electrons = # neutrons = An Anion!

Ions (Cont. ) • A Polyatomic Ion is an ion made of different elements

Ions (Cont. ) • A Polyatomic Ion is an ion made of different elements bound together. They can be positive or negative but are mostly negative. • Ex: NH 4+1; NO 2 -1; SO 4 -2; PO 4 -3. • Atoms acquire this charge by gaining or losing electrons from their outermost level = valence electrons.

Ions (Cont. ) • Why would an atom do this? Because… Atoms with a

Ions (Cont. ) • Why would an atom do this? Because… Atoms with a full valence shell are more stable. • The first level holds up to 2 electrons and all others hold 8. 8 8 2 P N

Perhaps one of you gentlemen would mind telling me just what is outside the

Perhaps one of you gentlemen would mind telling me just what is outside the window that you find so attractive!

Atoms & Ions

Atoms & Ions

More Atomic Theory • Protons, neutrons and electrons are known to be separated into

More Atomic Theory • Protons, neutrons and electrons are known to be separated into even smaller particles. • “Quark” is the term of all the other particles located in the nucleus of an atom. Some types of quarks combine to form a proton. Other types combine to form a neutron.

The Quark… Oops…wrong Quark!

The Quark… Oops…wrong Quark!

About Quarks… Protons and neutrons are NOT fundamental particles. Protons are made of two

About Quarks… Protons and neutrons are NOT fundamental particles. Protons are made of two “up” quarks and one “down” quark. Neutrons are made of one “up” quark and two “down” quarks. Quarks are held together by “gluons” Courtesy of Mr. Allen, El Diamante HS, Sciencegeeks. com

Build an Atom • http: //www. pbs. org/wgbh/aso/tr yit/atom/#

Build an Atom • http: //www. pbs. org/wgbh/aso/tr yit/atom/#

The average atomic mass can be • • • The Average atomic mass is

The average atomic mass can be • • • The Average atomic mass is the of an weighted • Three isotopes of argon occur in nature Ar calculated the mass atomic element average depends of the atomic on both masses the of the [(35. 97 amu x by 0. 337)+(37. 96 amu x -36, Ar-38, andmultiplying Ar-40. Calculate the mass each isotope itsofto relative average atomic mass of by argon two. 063)+(39. 96 amu x 99. 600)]/100 = of and naturally theofrelative occurring abundance isotopes ofeach an decimal places, given theinfollowing abundance(expressed decimalrelative the element’s isotopes. OR atomicand masses and the abundances of each of form) adding results. [(35. 97 amu x 0. 00337)+(37. 96 amu x the isotopes. . 00063)+(39. 96 amu x. 99600)] = • Ar-36(35. 97 amu; 0. 337%), 39. 94 amu • Ar-38(37. 96 amu; . 063%, and • Ar-40(39. 96 amu; 99. 600%)

3 Laws of Atomic Theory • Law of Definite Composition ─ a compound contains

3 Laws of Atomic Theory • Law of Definite Composition ─ a compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound • Example: teaspoon and a cup of sugar both are composed of 42. 1 % carbon, 51. 4% Oxygen & 6. 5% Hydrogen

Law of Definite Composition CO molecules are always composed of 1 carbon and 1

Law of Definite Composition CO molecules are always composed of 1 carbon and 1 oxygen. CO 2 molecules are always composed of 1 carbon and 2 oxygens

Law of Conservation of Mass • When two or more elements react to produce

Law of Conservation of Mass • When two or more elements react to produce a compound, the total mass of the compound is the same as the sum of the masses of the individual elements. • Matter and mass is neither created nor destroyed.

Law of Multiple Proportions • This applies to different compounds made from the same

Law of Multiple Proportions • This applies to different compounds made from the same element; the mass ratio for one of the elements that combines with a fixed mass of the other element can be expressed in a small whole number ratio.

Law of Multiple Proportions

Law of Multiple Proportions

Radioactivity • Atoms that “break down” are said to be radioactive. • There are

Radioactivity • Atoms that “break down” are said to be radioactive. • There are eight other naturally radioactive elements: polonium, astatine, radon, francium, radium, actinium, thorium and protactinium. • All other man-made elements heavier than uranium are radioactive as well.