Basic Chemistry: Atomic Structure, States of Matter, and Periodic Table

Atom

The smallest and most minute of all of the components of matter

Four states of matter

Solids, liquids, gases and plasma

Solids

A state of matter that is not as flexible as the other forms of matter in terms of the compressibility, shape and volume

Liquids

A state of matter that can change their shape according to the shape of the container it is poured into.

Gas

A state of matter that is compressible and has the ability to change their shape and volume according to the shape and size of the container that it is put into.

Plasma

A state of matter that found beyond the earth

Atomic structure

Atoms have a nucleus and electrons. Its nucleus contains protons and neutrons

Nucleus

The part of the atom that houses the protons and the neutrons

Protons

The positively charged (+) components of the atom. It is the number of protons that give the atom its chemical identity

Neutrons

The part of the atom that has no charge; they are neutral and without a positive or negative electrical charge; the part of the atom that gives the atom its isotope identity.

Electrons

The part of the atom that have a negative (-) charge.

Ion

An electrically charged atom

Cation

A positively charged atom

Anion

A negatively charged atom

The Periodic Table of Elements

Developed by the Russian chemist Mendeleev in the mid-1800s to display all known elements

What is an atom?

The smallest unit of matter that retains the properties of an element.

What are the three subatomic particles?

Protons, neutrons, and electrons.

Where are protons located and what is their charge?

In the nucleus, positive charge.

Where are neutrons located and what is their charge?

In the nucleus, neutral charge.

Where are electrons located and what is their charge?

Orbit the nucleus in energy levels, negative charge.

What is the nucleus of an atom?

Dense center containing protons and neutrons, responsible for most of the atom's mass.

What is the atomic number (Z)?

The number of protons in an atom; defines the element.

What is the mass number (A)?

The total number of protons + neutrons.

What are isotopes?

Atoms of the same element with different numbers of neutrons.

Give an example of isotopes.

Carbon‑12 and Carbon‑14.

How are electrons arranged?

In shells/orbitals around the nucleus.

How many electrons can the first shell hold?

2 electrons.

How many electrons can the second shell hold?

8 electrons.

What are valence electrons?

Electrons in the outer shell that determine chemical reactivity.

What is an ion?

An atom that gains or loses electrons.

What is a cation?

A positively charged ion (lost electrons).

What is an anion?

A negatively charged ion (gained electrons).

How is the periodic table organized?

By atomic number.

What do groups (columns) in the periodic table show?

Elements with similar valence electron configurations.

What do periods (rows) in the periodic table show?

Increasing energy levels.