Chapter 10 Atomic Structure and the Periodic Table

Objectives

• 10.1 List the names and symbols of common elements (Self Quiz)

• 10.1 Describe the present model of the atom • 10.1 Describe how electrons are arranged in

an atom • 10.2 Identify quarks as particles of matter that

make up protons and neutrons

Objectives

• 10.2 Explain how particle accelerators are used to study particles within atoms

• 10.3 Compute the atomic mass and mass number of an atom

• 10.3 Identify and describe isotopes of common elements

• 10.3 Interpret the average atomic mass of an element • 10.3 Determine the number of protons, neutrons,

and electrons an atom has from its symbol

Chemical Symbols

• Every element has a unique one or two letter abbreviation.

• Some elements symbols come from their Latin word (Aurum = Au = Gold)

• Next week’s quiz, need to memorize 20 elements and symbols (your choice)– Choose wisely

Objectives

• 10.4 Describe the periodic table of elements and use it to find information about an element

• 10.4 Distinguish between a group and a period • 10.4 Use the periodic table to classify an

element as a metal, non-metal, and metalloid • 10.4 Identify families on the periodic table • 10.4 Use the periodic table to determine the

number of valence electrons

Matter

– Composed of• Atoms

– Composed of• A Positive Nucleus• Negative Electrons Orbiting the Nucleus

Protons

• Have a Positive Charge– A +1 Charge

• Have a mass of 1 AMU – Atomic Mass Unit

• Found in the Nucleus• The Atomic Number is the number of Protons

an element has– On periodic table, the whole number integer (no

decimals)

SymbolAtomicMassotonsPr C12

6

Neutrons

• Have a neutral charge• Have a mass of 1 AMU• Found in the Nucleus• An atom’s mass is equal to the number of

Protons + the number of Neutrons– An element has 6 protons and 7 Neutrons. Its Atomic

Mass would be 13• On periodic table, the Average Atomic Mass is

Given (the number with decimals)

SymbolAtomicMassotonsPr

Electrons

• Have a negative charge– A -1 Charge

• Have a mass of 0 AMU– No Mass!

• As far as we are concerned, they weight approx 1/2000th of the mass of a proton. Might as well be nothing

• Found orbiting the nucleus• Neutral Atoms have EQUAL number of protons

and electrons

Bohr’s model of Atom• Electrons orbit the nucleus in “shells”•Only certain amount of electrons per shell

•1st Shell: 2 Electrons•2nd Shell: 8 Electrons•3rd Shell: 18 Electrons•4th Shell: 32 Electrons

Electron Cloud

• Shells called electron clouds– Since electrons move very quickly, hard to know

where they are (and Heisenberg Uncertainty principle). Instead, pictures often show a cloud.

• Cloud represents an allowed area to orbit for the electron, with roughly a 90% chance of finding the electron

Valence Electrons

How many outermost electrons? Maximum Number of 8

12 3 4 5 6 7

8

Are atoms the smallest?

• Protons and Neutrons are composed of Quarks– Quarks are the building blocks of atoms nuclei– 3 Quarks per Proton and Neutron– Electrons don’t have any quarks– How much deeper does the rabbit hole go?!

Atomic Mass

• Atomic Mass: Protons + Neutrons– Individual Atoms will have a whole number integer

mass– The Atomic Mass on Periodic Table is an average– Not all atoms of the same element have the same

mass. They differ in neutrons• These are called Isotopes

– Carbon – 12 and Carbon – 14 are both chemically Carbon, but weight different amounts

3545358035Br

1822184018Ar

2020204020Ca

e–n0p+MassAtomic

Practice Q’s

– Which atom(s) have 6 Neutrons?– Which atom(s) have an odd number of neutrons?– Which atom(s) have more neutrons than protons?– The ?? Is an isotope of which other atom?– Which atom(s) have 6 electrons?

C126 C14

6 N147 O16

8 ??167

SymbolAtomicMassotonsPr

Historical Perspective

• Mendeleev organized the periodic table (same guy who did the punnett square)

• Really smart guy, left blanks in where he thought that another element would be discovered and predicted the properties of the element

Development of Periodic Table

Mendeleev, for instance, predicted the discovery of germanium (which he called eka-silicon) as an element with an atomic weight between that of zinc and arsenic, but with chemical properties similar to those of silicon.

Historical Perspective

• The periodic table is organized by groups. • Each group has similar properties (vertical

columns)– Oxygen is similar to Sulfur is similar to Selenium

• This is all because of having similar valence electron configurations (same outer shell)

Mendeleev’s table

Development of Periodic Table

• Elements in the same group generally have similar chemical properties.

• Properties are not identical, however.

Development of Periodic Table

Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.

Key Terms 10.4

• Metal• Nonmetal• Metalloid• Semiconductor

– Conductor– Insulator

• Transition Elements• Lanthanide• Actinide• Alkali Metals• Alkaline Earth Metals• Halogens• Noble Gases

Periodic Table

Metals

Properties of Metals

• Luster• Conductors (Heat/Electrons)• Malleable• Ductile• Most are solid at room temperature• Loosely held valence electrons

Nonmetals

Properties of Nonmetals

• Insulators• Brittle• Dull• Many are gases at room temperature• Tightly held valence electrons

Semi-metals or Metalloids

Metalloids

• Have properties of both– Instead of thinking an element is purely a metal or

only a nonmetal, think of the periodic table as a spectrum.

– Lower left is the best metal, as you move towards the top right, you lose your metal properties and become more of a nonmetal

– Metalloids are in the middle– What metal and nonmetal properties does Gold

have?

Properties of Metal, Nonmetals,and Metalloids

Alkali Metals One Word: First Column

Alkaline Earth MetalsTwo Words: Second Column

Halogens (Name: Salt Maker)

Noble Gases (Inert Gases)

Lanthanide and Actinide

Transition Metals