Atomic Structure & Properties: Essential Chemistry Concepts

Unit 3, Part 1: Core Chemistry Principles

Transition Metals: Unique Properties Explained

It is surprising that transition metals exhibit similar physical and chemical properties despite having varying numbers of valence electrons.

Unlocking Information from the Periodic Table

The periodic table is a powerful tool from which you can determine:

• Number of protons
• Number of neutrons
• Number of electrons
• Atomic mass
• Atomic number
• Element name
• Atomic symbol
• Valence electron shells
• Total electron shells

Defining Atomic Identity: The Proton

The proton defines the identity of an atom. Its number corresponds to the atomic number, which uniquely identifies each element. The number of protons in an atom never changes.

Subatomic Particle Locations

Each subatomic particle has a specific location within the atom:

• Protons and neutrons are located inside the nucleus.
• Electrons are located outside the nucleus, in electron shells.

Nucleons: The Heart of the Atom

Nucleons refer to the protons and neutrons of an atom. They are located together in the atom's nucleus.

Charges of Subatomic Particles

Proton charge:

+1 (positive)

Electron charge:

-1 (negative)

Neutron charge:

0 (neutral)

Where is the Mass of an Atom Concentrated?

The mass of an atom is primarily concentrated in its nucleus, where protons and neutrons reside. Only protons and neutrons possess sufficient mass to significantly contribute to the atom's overall mass.

Why Electron Mass is Excluded

The mass of an electron is not included in the overall mass of the atom because it is exceedingly small and light compared to protons and neutrons.

Understanding Valence Electrons

Valence electrons are the electrons located in the outermost electron shell of an atom. They play a crucial role in chemical bonding.

Element vs. Compound: Key Distinctions

An element is a pure substance found on the periodic table that cannot be broken down into simpler substances by chemical means. A compound is formed when two or more different elements chemically bond together. Unlike elements, compounds can be broken down into their constituent elements through chemical reactions.

Atomic Mass vs. Mass Number Explained

Atomic Mass:

The weighted average of the masses of all naturally occurring isotopes of a specific element.

Mass Number:

The sum of the number of protons and neutrons in a single atom's nucleus.

Why Atoms Are Electrically Neutral

An atom's overall charge is neutral because it contains an equal number of positively charged protons and negatively charged electrons. These equal and opposite charges effectively cancel each other out.

Calculating Mass Number

The Mass Number of an atom is calculated as follows:

PROTONS + NEUTRONS = MASS NUMBER