Chapter 4 - Atoms and Elements

Primary substances of matter are elements.
Chemical symbols are abbreviations of element names in a single or two-letter way.

A periodic table is an atomic number that increases the arrangement of the elements.
- The time is called a horizontal row
An element with similar properties is called a group in the vertical column on the periodic table.
Group 1a(1) is known as alkali, Group 2A(2) is referred to as alkaline earth, Group 7A(17) is known as halogens, and Group 8A(18) contains noble gasses.
- The metals are on the left side of the heavy zigzag line on the periodic table and nonmetals are on the right-hand side of the heavy zigzag line.
- With the exception of aluminum, metalloids are called elements along the heavy zigzag line.

An atom is the smallest particle to preserve an element's characteristics
Three kinds of subatomic particles consist of atoms
- Positive protons (+), negative charges of electrodes (-), and electrically neutral neutrons.
In the small, dense nucleus, the protons and neutrons are found; electrons are outside the nucleus.

In all atoms in the same element, the atomic number indicates the number of protons.
- The number of protons and electrons in a neutral atom is identical
The total number of protons and neutrons in a nucleus is the mass number.

Isotopes are called atoms that have the same proton number, but various neutron numbers.
The element's atomic weight consists of the average mass of all isotopes in a natural sample.

Each electron is energy-specific.
- Electrons of similar energy in an atom are grouped into specific levels of energy.
The second level holds up to 8 electrons and the third level holds up to 18 electrons.
- The first level is closest to the core.
The arrangement of electrons is written in order to place the number of electrons in this atom from the lowest energy level to the highest.

The element characteristics are linked to atom valence electrons.
- With only a few exceptions, the same arrangement of valence electrons only differs in energy level for each group of elements
The electrons of Valence are represented as points around the element symbol
The size of an atom increases from left to right over a period, going down a group.
- The energy needed to remove a valence electron is the energy of ionization, which decreases over time and goes from left to right.
The metallic nature of an element increases the number of people going down and decreases throughout a period from left to right.