Chemistry Unit 2: Atomic Structure

Bohr Model of the Atom (Explain what it shows and list one con for this model.)

-Electrons orbit around the nucleus. -Each orbit has a fixed energy called an energy level. -To move from one energy level to another, an electron must gain or lose just the right amount of energy. -Each energy level has a different energy. -The further from the nucleus the energy level is, the more energy it has. Con: Electrons bounce around, not orbit.

Quantum Mechanical Model (Who was it made by and what did it show?)

-Made by Schrodinger to describe the behavior of an electron. -The model doesn't specify the exact path the electron takes around the nucleus. -It determines the allowed energies an electron can have and how likely it is to find an electron in various locations around the nucleus.

For each energy level, state the sublevel.

1 - 1s 2 - 2 s, p 3 - 3 s, p, d 4 - 4 s, p, d, f

A sample of copper with a mass of 63.5 g contains 6.02*10^23 atoms. Calculate the mass of one atom of copper using dimensional analysis.

1 atom Cu * 63.5 g/6.02 * 10^23 = 1.05 *10^-22g

What are the four parts of Dalton's atomic theory?

1. All elements are composed of tiny particles called atoms. 2. Atoms of the same element are identical. 3. Atoms of different elements can be mixed together and chemically combine forming a compound. 4. Chemical reactions occur when atoms are separated, joined, or rearranged.

Orbital Notation and Electron Configuration

1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^10, 4p^6, 5s^2, 4d^10, 5p^6, 6s^2, 4f^14, 5d^10, 6p^6, 7 s^2, 5f^14, 6d^10, 7p^6.

Who was Democritus?

A Greek philosopher who lived over 2000 years ago, and was among the first to suggest the existence of atoms.

Uncontrolled Nuclear Chain Reaction

Atomic Bomb (U-235)

Periodic Table Notation

Atomic Number Element Symbol Atomic Mass

Isotopes

Atoms that have the same number of protons but different number of neutrons. (Example: Different types of carbon like Carbon 12, Carbon 13, and Carbon 14.)

How did Democritus describe an atom?

Atoms were indivisible and indestructible.

Alpha Particles (What are they composed of, what are the symbols for it, and what is the penetrating power?)

Composed of: 2 Protons and 2 Neutrons. Symbols: 4/2 He or a symbol (partially done infinity loop.) Penetrating Power: Low (Wouldn't go through paper.)

Transmutation

Conversion of an atom of one element into an atom of another element. It can occur by radioactive decay or when particles bombard the nucleus of an atom.

Sublevel

Corresponds to one or more orbitals of different energy, which describes where an electron is likely to be found. Examples: s, p, d, and f orbitals.

Explain why the ideas on atoms proposed by Dalton constitute a theory, while the ideas proposed by Democritus do not.

Democritus's approach wasn't based on the scientific method, but Dalton followed the scientific method, transforming Democritus's idea in a theory.

Energy Level

Describes how far an electron is from the nucleus. (1, 2, 3, 4, etc.)

Pauli Exclusion Principle

Each orbital can hold a maximum of 2 electrons and the maximum have opposite spins. (Example: Hotel rooms activity - 2 kids in a room, one has the top bunk, other has the bottom bunk.)

Hund's Rule

Electron pairing only occurs after all orbits are filled with a single electron. (Example: Hotel rooms activity - Trying to get kids their own rooms.)

Aufbau Principle

Electrons occupy the orbitals of the lowest energy level first. (Example: Hotel rooms activity - Lowest floor to the ground as possible.)

What are the three types of radiation?

Gamma, alpha, and beta radiation.

What happens in a nuclear reaction?

Giving off radiation or energy, the atom becomes more stable.

State Rutherford's outcome of his experiment.

He launched protons through a gold foil, and the gold foil has some empty space, but some of it contains the nuclei of the atoms. If a proton hit one of the nuclei, it bounces off the nucleus and it doesn't go strait through the gold foil.

Who was John Dalton?

He used the experimental methods to transform Democritus's ideas on atoms into a scientific theory in the early 1800s.

Fission

Large nuclei split apart and form smaller nuclei. Example: Nuclear reactor.

What must be balanced in nuclear reactions?

Left side and right side of the equation have to make sense (mathematically) and be balanced.

Beta Particles (What is it made of, what is the symbol, and what is its penetrating power?)

Made of: Electron Symbols: B and 0/-1 e Penetrating Power: Moderate (Will go through paper but not wood.)

Gamma Rays (What is it made of, what is the symbol, and what is its penetrating power?)

Made of: Not made up of particles; have no charge. Symbol: Y Penetrating Power: Very high (enters body easily.)

How do you calculate the number of neutrons in an atom?

Mass Number - Atomic Number = Number of Neutrons.

Isotope Notation

Mass Number Element Symbol Atomic Number

How do you calculate atomic mass?

Multiply the mass of each isotope by its percent abundance and add the results. Use the periodic table to confirm the calculation and identify the element.

What are the charges and relative masses of the three main subatomic particles?

Proton P+, 1+, 1 amu Neutron n°, 0, 1 amu Electron e-, 1-, 1/1840 amu (0 amu)

Particles Involved in Nuclear Reactions (Name, symbol, and charge.)

Proton, 1/1 P, +1 Neutron, 1/0 n, 0 Alpha Particle, 4/2 He, +2 Electron (Beta Particle,) 0/-1 e (or B) -1 Positron, 0/+1 e, +1 Gamma, Y, 0

How do you calculate the mass number?

Protons + Electrons = Mass Number.

What are the three types of subatomic particles that make up an atom?

Protons, neutrons, and electrons.

Atomic Orbitals

Region in which there is a high probability of finding an electron.

What instrument can be used to observe individual atoms?

Scanning electron microscopes.

Fusion

Small nuclei combine and release much more energy than fusion. Example: Sun.

Atom

Smallest particle of an element that retains its identity in a chemical reaction.

Chain Reaction

Some of the emitted neutrons react with other atoms which emit more neutrons and nuclei.

What happens when an atom loses a beta particle?

The atomic number of the product is increased by 1 and its mass number stays the same.

What happens when atoms lose an alpha particle?

The atomic number of the product is lowered by 2 and its mass is lower by 4.

What experimental evidence led Rutherford to conclude that an atom is mostly empty space?

The lack of deflected protons tells that it's mostly empty space.

Describe Rutherford's model of the atom.

The nucleus has all positive charge, and contains almost all the mass of the atom in a small, concentrated space.

The number of protons =

The number of electrons.

Atomic Number

The number of protons in an atom, and found on the periodic table as a whole number.

Nuclear Radiation

The rays and particles emitted from a radioactive source.

Radioactivity (Radioactive Decay)

The spontaneous emission of rays or particles from certain elements.

Half-Life (t1/2)

The time required for one-half of the nuclei in a radioisotope sample to decay to products (atoms of a new element.)

Electron Configuration

The way in which electrons are arranged in orbitals around the nucleus.

Atomic Mass

The weighted average mass of all the isotopes of that element. The number appears on most periodic tables (# with decimal places.)

Describe Thomson's and Millikan's contributions to atomic theory.

Thomson passed electric currents at low pressure through a gas filled tube and discovered electrons, and Millikan discovered electron charge and mass.

How are masses of individual atoms measured?

Use atomic mass unit (amu) to measure masses of individual atoms.

What do nuclear power plants use to produce energy?

Use neutron moderation and neutron absorption.

For each sublevel, state the number of orbitals in a sublevel and the number of electrons in a sublevel.

s - 1, 2 p - 3, 6 d - 5, 10 f - 7, 14