Atomic Structure

Chemistry SOL Review by Anne Mooring (Jamestown High School, Williamsburg VA, 2006)

Part 2: Atomic Structure and Periodic Relationships 1. Parts of the Periodic Table 2. Introduction to the SOL Periodic Table 3. Atomic Structure and the Periodic Table 4. Periodic Trends in Atomic Radius, Ionization Energy, and Electronegativity. 5. Isotopes and Average Atomic Mass 6. Historical and Quantum Models of the Atom A calculator will be helpful, but not necessary for this powerpoint.

This section represents 8/50 of the SOL questions

The columns are called groups or families. Groups have similar physical and chemical properties and the same number of valence electrons

Name the groups boxed in yellow, orange, green and blue.

Name the groups boxed in yellow, orange, green and blue. Alkali metals, Alkaline Earth metals, Halogens, and Noble or Inert Gases.

The rows are called periods. The period number matches the principle energy level of the element. This will be the principle energy level of the valence electrons.

What is the principle energy level of Nickel, Ni?

What is the principle energy level of Nickel, Ni? 4—it is in the row numbered 4

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Click on the link to get the SOL periodic table Keep this Adobe file open as you work on the review Let’s use the periodic table to answer some questions about Silicon

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have?

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have?

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have? 14 electrons (# electrons = # protons in neutral atoms) How many neutrons does Silicon-30 have?

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have? 14 electrons (# electrons = # protons in neutral atoms) How many neutrons does Silicon-30 have? 16 neutrons. Silicon-30 is an isotope of Silicon. It has a mass number of 30. The mass number is protons + neutrons.

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have? 14 electrons (# electrons = # protons in neutral atoms) How many neutrons does Silicon-30 have? 16 neutrons. Silicon-30 is an isotope of Silicon. It has a mass number of 30. The mass number is protons + neutrons. What is the molar mass of Silicon?

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have? 14 electrons (# electrons = # protons in neutral atoms) How many neutrons does Silicon-30 have? 30 neutrons. Silicon-30 is an isotope of Silicon. It has a mass number of 30. The mass number is protons + neutrons. What is the molar mass of Silicon? 28.0855 grams/mole (this is the same as the atomic mass on the periodic table)

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have? 14 electrons (# electrons = # protons in neutral atoms) How many neutrons does Silicon-30 have? 30 neutrons. Silicon-30 is an isotope of Silicon. It has a mass number of 30. The mass number is protons + neutrons. What is the molar mass of Silicon? 28.0855 grams/mole (this is the same as the atomic mass on the periodic table) How many valence electrons does Silicon have?

Chemistry SOL Review—Atomic Structure Using the SOL Periodic Table Let’s use the periodic table to answer some questions about Silicon. How many protons does Silicon have? 14 protons = atomic number. How many electrons does neutral Silicon have? 14 electrons (# electrons = # protons in neutral atoms) How many neutrons does Silicon-30 have? 30 neutrons. Silicon-30 is an isotope of Silicon. It has a mass number of 30. The mass number is protons + neutrons. What is the molar mass of Silicon? 28.0855 grams/mole (this is the same as the atomic mass on the periodic table) How many valence electrons does Silicon have? 4 valence electrons. Look for electrons in the highest principle energy level.

Chemistry SOL Review—Atomic Structure

An s orbital holds 2 electrons w/ opposite spins

Chemistry SOL Review—Atomic Structure

Each p orbital holds 2ewith opposite spins

Chemistry SOL Review—Atomic Structure

Each d orbital holds 2ewith opposite spins

Chemistry SOL Review—Atomic Structure The orbitals and the periodic table

The s suborbital fills

Chemistry SOL Review—Atomic Structure The orbitals and the periodic table

The p suborbitals fill

Chemistry SOL Review—Atomic Structure The orbitals and the periodic table

The d suborbitals fill

Chemistry SOL Review—Atomic Structure Valence electron configuration and the periodic table

All group 13 elements have the valance electron configuration ns2np1.and 3 valence electrons

Chemistry SOL Review—Atomic Structure Valence electron configuration and the periodic table

All group 15 elements have the valance electron configuration ns2np3.and 5 valance electrons.

Chemistry SOL Review—Atomic Structure Valence electron configuration and the periodic table

What is the valence configuration of the halogens?

Chemistry SOL Review—Atomic Structure Valence electron configuration and the periodic table

What is the valence configuration of the halogens? ns2np5.

Chemistry SOL Review—Atomic Structure Periodic Trends in Atomic Radius, Ionization Energy, and Electronegativity. Atomic Radius: the radius of an atom in picometers First Ionization Energy: The energy needed to remove the first valence electron from a gaseous atom. Electronegativity: The tendency of an atom to attract electrons to itself when chemically combined with another element.

Chemistry SOL Review—Atomic Structure Periodic Trends in Atomic Radius, Ionization Energy, and Electronegativity. Atomic Radius: the radius of an atom in picometers

1

2

13

14

15

16

17

18

Chemistry SOL Review—Atomic Structure Periodic Trends in Atomic Radius, Ionization Energy, and Electronegativity. First Ionization Energy: The energy needed to remove the first valence electron from a gaseous atom. Ionization energy increases as you move to higher number groups. Group 18 has the highest 1st ionization energy. Ionization energy decreases as you move down the periodic table.

Chemistry SOL Review—Atomic Structure Periodic Trends in Atomic Radius, Ionization Energy, and Electronegativity. First Ionization Energy: The energy needed to remove the first valence electron from a gaseous atom.

Chemistry SOL Review—Atomic Structure Periodic Trends in Atomic Radius, Ionization Energy, and Electronegativity. Electronegativity: The tendency of an atom to attract electrons to itself when chemically combined with another element.

The halogen group has the highest electronegativity of the families. The first period has the highest electronegativity. Noble gases do not have electronegativity as the valence shell is already full.

Chemistry SOL Review—Atomic Structure Anions, Cations, and Electron Configuration Cations form by losing valance electrons to take on a noble gas configuration (ns2np6)

Chemistry SOL Review—Atomic Structure Anions, Cations, and Electron Configuration Cations form by losing valance electrons to take on a noble gas configuration (ns2np6)

So Li loses the 2s1 electron to form Li+1 . Mg loses both 3s2 electrons to form Mg+2 Al loses three electrons from 3s23p1 to form Al+3

Chemistry SOL Review—Atomic Structure Anions, Cations, and Electron Configuration Anions form by gaining valance electrons to take on a noble gas configuration (ns2np6)

So F becomes F1- by gaining a 2p electron to have the new valance configuration 2s22p6. S becomes S2- by gaining two 2p electrons to have the new valance configuration 3s23p6. N becomes N3- by gaining three 2p electrons to have the new valance configuration 2s22p6.

Chemistry SOL Review—Atomic Structure

Isotopes: elements with the same number of protons, but a different number of neutrons.

12 C 6

13 C 6

Carbon-14 has ___ protons and ___ neutrons

14 C 6

Chemistry SOL Review—Atomic Structure

Isotopes: elements with the same number of protons, but a different number of neutrons.

12 C 6

13 C 6

Carbon-14 has 6 protons and 8 neutrons

14 C 6

Chemistry SOL Review—Atomic Structure

Isotopes: elements with the same number of protons, but a different number of neutrons.

12 C 6

13 C 6

14 C 6

You figure out the average atomic mass of a compound by using a weighted average of the mass number for each isotope. Example: a sample contains 10% C-13, 60% C-12 and 40% C-14. The average atomic mass is

(0.10 x 13) + (0.60 x 12) + (0.30 x 14) = 12.7

Chemistry SOL Review—Atomic Structure

Development of the Atomic Model • • • •

Thompson Model Rutherford Gold Foil Experiment and Mode Bohr Model Quantum-Mechanical Model

From Mark Rosengarten’s New York Regent’s Powerpoint

Chemistry SOL Review—Atomic Structure

Thompson Model • The atom is a positively charged diffuse mass with negatively charged electrons stuck in it.

From Mark Rosengarten’s New York Regent’s Powerpoint

Chemistry SOL Review—Atomic Structure

Rutherford Model • The atom is made of a small, dense, positively charged nucleus with electrons at a distance, the vast majority of the volume of the atom is empty space. Alpha particles shot at a thin sheet of gold foil: most go through (empty space). Some deflect or bounce off (small + charged nucleus).

From Mark Rosengarten’s New York Regent’s Powerpoint

Chemistry SOL Review—Atomic Structure

Bohr Model • Electrons orbit around the nucleus in energy levels (shells). Atomic bright-line spectra was the clue.

From Mark Rosengarten’s New York Regent’s Powerpoint

Chemistry SOL Review—Atomic Structure

Quantum-Mechanical Model • Electron energy levels are wave functions. • Electrons are found in orbitals, regions of space where an electron is most likely to be found. • You can’t know both where the electron is and where it is going at the same time. • Electrons buzz around the nucleus like gnats buzzing around your head.

From Mark Rosengarten’s New York Regent’s Powerpoint