Unit 3: Atomic Structure

Electron

(e-) negative particle outside of the nucleus in the electron cloud

Neutron

(n0) neutral particle in the the nucleus with protons

Proton

(p+) positive particle in the nucleus

Draw a timeline of the structure of an atom - 1

1. 400BC: Democritus was the first to name the atom 2. 1803: John Dalton discovered that atoms are a solid sphere that makes up elements 3. 1904: JJ Thomson's Plum Pudding Model showed atom is divisible, positively charged spheres with negative particles throughout

Draw a timeline of the structure of an atom - 2

1911: Ernest Rutherford's Nuclear Model says that most of the atom's mass is with the positively charged particles in the nucleus 1913: Henry Moseley discovered the number of protons is unique to each element 1926: Schrodinger and Heisenberg's Electron Cloud Model showed that the nucleus is surrounded by an electron cloud that is divided into shells

Periods

the horizontal rows on the periodic table

Summarize our current understanding of atomic structure. Include the two parts, where the three particles are located, and where the mass and volume in an atom mainly exist.

An atoms structure consists a nucleus, where most of the mass is, and an electron cloud, where most of the volume is. The electrons are located in the electron cloud, and the protons and neutrons are located in the nucleus.

Isotopes

Atoms of the same element with different of neutrons

Explain why elements in the same group have similar properties.

Because all elements in the same group have the same number of valence electrons.

Valence Electron

Electrons on the outermost energy level of an electron cloud

Describe the pattern/shared characteristics of elements in the same group vs. the same period.

Elements in the same group have the same number of valence electrons. Elements in the same period have the same number of energy levels.

List the names and any special characteristics for groups 1, 2, 3, 3-12, 17, and 18.

Group 1: Alkali metals are the most reactive metals (not hydrogen) Group 2: Alkaline earth metals Group 3: Rare earth metals Groups 3-12: Transition metals Group 17: Halogens are the most reactive non-metals Group 18: Noble gases are non-reactive elements

Write in both hyphen and nuclear notation the most common isotope for lithium.

Hyphen: Lithium - 7 Nuclear: 7*Li

Differentiate between the characteristics of metals, nonmetals, and metalloids. Include their general location on the periodic table.

Metals: shiny, silvery solids that conduct heat well and are to the left of metalloids Metalloids: Solid, semiconductors that are physically like metals, chemically like nonmetals to the left of non metals Non metals: Poor conduction gases or non brittle solids that are on the right of the table (except for hydrogen)

Mass number

Tells the number of protons and neutrons in the nucleus of an atom

Atomic Number

Tells the number of protons in an atom of the element

Differentiate between the Bohr Model and the Electron Cloud Model

The Bohr Model states the electrons move in a fixed orbit around the positively charged nucleus. The Electron Cloud Model says that the electrons travel in an electron cloud, but not in a fixed orbit.

Explain the three forces at work that hold an atom together.

The attractive force between the nucleus and electrons hold the atom together, the repulsive force between electrons gives the electron cloud volume, and the repulsive force between the protons holds the nucleus together.

Explain the structure of the electron cloud. Include how many electrons are held on each level, where valence electrons are, and which electrons are the craziest.

The electron cloud is broken into energy levels. Valence electrons are on the outermost energy level and are the craziest. There are two electrons on the first energy level, and the number of electrons on the outermost level is based on the group. Levels 2 and 3 hold up to 8 electrons.

Quark

The smallest known particles that make up

Atom

The smallest particle of an element that still has the properties of that element

Groups

The vertical columns on the periodic table

Explain what two isotopes of the same element have in common and what is different about them. Include when an isotope is considered to be the most stable.

Two isotopes of the same element have the same number of protons, but different number of neutrons. An isotope is most stable when the number of protons and neutrons are the same.

Average atomic mass

Weighted average of all the different versions of an element

Explain what it means for an atom to be electrically neutral.

When an atom is electrically neutral, it means it has the same number of protons and neutrons.

Magnesium a. atomic number b. mass number c. protons d. neutrons e. electrons

a. 12 b. 24 c. 12 d. 12 e. 12

Arsenic a. atomic number b. mass number c. protons d. neutrons e. electrons

a. 33 b. 75 c. 33 d. 42 e. 33

Use the periodic table to determine the identity of each element described below. a. The first element in group 13. b. A period 2 nonmetal with 6 valence electrons. c. A metalloid with 71 neutrons. d. A gas with 2 valence electrons and 1 energy level in its electron cloud.

a. Boron b. Oxygen c. Antimony d. Helium

Use the periodic table to determine the identity of each group described below. a. Their atoms have 5 valence electrons. b. They are the most reactive metals. c. They are the most reactive nonmetals. d. They do not react in nature.

a. Group 15: Nitrogen Group b. Group 1: Alkali metals c. Group 17: Halogens d. Group 18: Noble gases

Which numbers tell you the following: a. The number of protons in an element b. The number of protons and neutrons in an element c. The number of total electrons d. The identity of an element e. The most common form of an element

a. atomic number b. mass number c. atomic number d. atomic number e. average atomic mass