Chemistry - Chapters 3 & 4: The Atom And The Atom Structure

Describe how the model of the atom changed from the time of the Greek philosophers in (400 B.C.) to the time of Thomson and Rutherford (1900’s A.D.)?

Describe how the model of the atom changed from the time of the Greek philosophers in (400 B.C.) to the time of Thomson and Rutherford (1900’s A.D.)?

The model of the atom changed over time from a simple structure with no nucleus and no subatomic particles (400 B.C.) to a complex structure with positively charged nucleus containing protons (+) and neutrons (0) and electrons (-) in orbitals surrounding the nucleus

Briefly explain 4 parts of Dalton’s Atomic Theory

1. All matter is composed of atoms. Atoms of an element are identical, atoms of different elements have different sizes and masses.

2. Atoms cannot be broken down into simpler substances.

3. Atoms cannot be created or destroyed in a chemical reaction.

4. Atoms rearrange in chemical reactions to produce new compounds.

How big is an atom? Can you see an atom? Explain why or why not?

The atom is about 10^-10 meters (or 10^-8 centimeters) in size. This means a row of 10⁸ (or 100,000,000) atoms would stretch a centimeter, about the size of your fingernail. No, you cannot see an atom.

What are the three types of subatomic particles?

Proton, Neutron, and Electron

What is the PROTON’S Symbol, Charge, Location, and Approximate Relative Mass

• Symbol: p⁺

• Charge: +1

• Location: Nucleus of an atom

• Approximate Relative Mass: 1 amu (atomic mass unit).

What do PROTONS deterimine in an element

Protons determine the atomic number and identity of an element

What is the NEUTRON'S Symbol, Charge, Location, and Approximate Relative Mass

• Symbol: n⁰

• Charge: 0 (neutral)

• Location: Nucleus of an atom

• Approximate Relative Mass: 1 amu (atomic mass unit)

What is the ELECTRON'S Symbol, Charge, Location, and Approximate Relative Mass

• Symbol: e^-

• Charge: -1 (negative)

• Location: Orbiting the neucleus

• Approximate Relative Mass: 0 amu (atomic mass unit)

What does the ATOMIC NUMBER tell you? Where do you find the atomic number on the periodic table?

Atomic number tells the number of protons in the nucleus of atom.

Whole number in top corner of element’s symbol on periodic table.

What does the MASS NUMBER tell you? Where do you find the atomic number on the periodic table?

Atomic mass is the weighted average of all the isotopes of an element. (Decimal # on periodic table)

Mass number tells the number of protons and neutrons contained in the nucleus of an atom. (Rounded)

1 amu = atomic mass unit

Name the ELECTROMAGNETIC SPECTRUM

In order from highest to lowest energy: gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

List in order the seven colors of the visible light spectrum from HIgh energy to Low Energy

Violet, indigo, blue, green, yellow, orange, red

Which of the seven colors of the visible light spectrum has the highest energy? Lowest Energy?

Highest energy = Violet

Lowest energy = Red

Which of the seven colors of the visible light spectrum has the highest frequency? Lowest frequency?

Highest frequency = Violet

Lowest frequency = Red

Which of the seven colors of the visible light spectrum has the longest wavelength? Shortest wavelength?

Longest Wavelength = Red

Shortest Wavelength = Violet

What is a CATION and how does it form?

A cation is a positively charged ion formed when a neutral atom loses an electron.

Metals tend to lose electrons and form cations.

What is an ANION and how does it form?

An anion is a negatively charged ion formed when a neutral atom gains an electron.

Non-metals tend to gain electrons and form anions.

What is an isotope? Name 2 ways that isotopes of the same element are different

Isotopes have the same number of protons, different number of neutrons

Isotopes have same atomic number, different mass number

How can there be more than 1000 different atoms when there are only about 118 different elements?

There are many isotopes of the same element. Each isotope has a different mass and size, but they are identical elements because they have the same number of protons and behave with similar chemical properties. The atomic mass of each element listed on the periodic table is a weighted average of all isotopes of that element. 

Laboratory: Explain how flame tests can be used to identify the metal present in an unknown compound? Explain how an atom’s electron emits light energy when excited.

Each metal gives off a different color flame because each element has different number of electrons. As the electron gets excited by heat of flame, it moves from a higher energy level to a lower energy level and emits excess energy as light.

How do you calculate the atomic mass of an element? What is the unit a.m.u?

Calculate the atomic mass by multiplying the mass of each isotope by its natural abundance and then adding the sum of the masses in decimal form.