Atom Structure and Isotopes

Study Notes

Atom Structure

Protons, Neutrons, and Electrons
- Protons are positively charged particles located in the nucleus.
- Neutrons are neutral particles located in the nucleus.
- Electrons are negatively charged particles that orbit the nucleus.
Atomic Mass Unit (amu)
- Protons and neutrons each have a mass of approximately 1 amu.
- Electrons have a very small mass, almost negligible.

Isotopes

Definition: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
Properties:
- Isotopes of the same element share similar chemical properties but can have slightly different physical properties.
- This difference in physical properties can be attributed to the variation in mass caused by different numbers of neutrons.

Periodic Table Organization

Invention: Dmitri Mendeleev invented the periodic table in the 1800s.
Main Categories:
- Metals: Elements on the left side of the periodic table that are generally shiny, malleable, ductile, good conductors of heat and electricity.
- Non-metals: Elements on the right side of the periodic table that are generally not shiny, not malleable, not ductile, poor conductors of heat and electricity.
- Metalloids (semimetals): Elements found along the border between metals and non-metals, possessing properties of both.

Periodic Table Structure

Periods (Horizontal Rows): Elements in the same period have the same number of electron shells or energy levels.
Groups/Families (Vertical Columns): Elements in the same group have similar chemical properties due to sharing the same number of electrons in their outermost shell, also known as valence electrons.

Key Groups

Group 1: Alkali Metals

Examples: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr)
Valence Electrons: 1
Physical Properties:
- Solid at room temperature
- Shiny, silvery color
- Soft metals
Chemical Properties:
- Highly reactive
- React with water to produce hydrogen gas
- Exist in nature only as compounds
- Lose 1 electron to form +1 ions

Group 2: Alkaline Earth Metals

Examples: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra)
Valence Electrons: 2
Physical Properties:
- Solid, denser than Group 1 metals
- Metallic
Chemical Properties:
- Reactive, although less than Group 1 metals
- Exist in nature only as compounds
- Lose 2 electrons to form +2 ions

Group 17: Halogens

Examples: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At), Tennessine (Ts)
Valence Electrons: 7
Physical Properties:
- Non-metals
- Varied states:
  - Fluorine (F) is a yellow gas
  - Chlorine (Cl) is a yellow-green gas
  - Bromine (Br) is a red-brown liquid
  - Iodine (I) is a violet/black solid
Chemical Properties:
- Highly reactive and corrosive
- Exist in nature only as compounds

Description

Explore the fundamentals of atom structure, including protons, neutrons, electrons, and isotopes. This quiz examines atomic mass units and the organization of the periodic table. Understand how isotopes differ in physical properties while maintaining similar chemical characteristics.