Download Chemistry Study Guide What is matter made of? Matter is anything

Chemistry Study Guide
What is matter made of?
Matter is anything that has mass and volume.
All matter is made up of atoms, which are called the building blocks of matter. An atom has three main parts:
protons, neutrons, and electrons.
Protons and neutrons make up the center of the atom, the nucleus. Electrons orbit the outside of the nucleus.
Protons and electrons have electrical charges:
Each proton has a positive (+) charge.
Each electron has a negative (-) charge.
A neutron is neutral. It has no charge.
An atom has the same number of protons and electrons.
Number of protons = Number of electrons
This means the number of positive charges equals the number of negative charges. They balance each other; the
entire atom has no charge, neutral.
How are electrons arranged around the nucleus?
The electrons’ movements are arranged into energy levels called shells.
Each shell can hold only a certain number of electrons.
● The first shell (nearest the nucleus) is the “K” shell. It can hold only 2 electrons
● The second shell is the “L” shell. It can only hold 8 electrons.
● The “M” shell is the third shell. It can hold up to 18 electrons, unless it is the outermost shell. Then it
can only hold up to 8 electrons.
The number of shells an atom has depends upon its number of electrons. Each shell must have its full number of
electrons before a new shell starts.
The outer shell of most electrons is not full. Only the atoms of the elements of Group 18 have full outer shells.
● Atoms of most metals have fewer than 4 outer shell electrons.
● Atoms of nonmetals usually have more than 4 outer-shell electrons.
Matter made up of only one kind of matter called an element. There 118 kinds of elements. That is one element
for each kind of atom. There are 92 naturally occurring elements.
Elements are unique, pure substances.
Elements and the Periodic Table
Elements are arranged in order of their atomic number. The atomic number of an element is the number of
protons in the nucleus of an atom of that element. Every element has its own atomic number.
The periodic table has horizontal and vertical rows (run up and down). Each vertical row (column) is called a
group, or family. All of the elements in a column belong to the same group. Elements in the same group have
properties that are the same or very similar. The elements in each group also have the same number of
electrons in their outer shell.
The horizontal rows are called periods. The elements in each period are arranged by atomic number and have
the same number of electron shells around the nucleus.
Each elemental tile:
20
Ca
Calcium
40.08
In most cases, the chemical symbol is the first or first and second letter of the element’s name. However, with
elements such as tin (Sn), gold (Au), or lead (Pb) the Latin initials are used. If two letters are used for a
chemical symbol the first letter is always capital (upper case) and the second letter is always lower case.
The atomic number is equal to the number of protons in the element, but it is also equal to the number of
electrons that orbit the nucleus of the atom.
Atomic number = protons = electrons
Example: Carbon’s atomic number is 6. The number of protons is 6. The number of electrons is 6.
Atomic Mass:
The number of parts in an atom’s nucleus. Therefore, the number of protons plus the number of neutrons is the
atomic mass. (Usually the decimal number)
Calculating Neutrons
To calculate the number of neutrons, subtract the atomic number from the atomic mass. Round the atomic mass
to the nearest whole number. > .5 or greater round up.
Coefficients: a number that shows how many molecules of a substance are involved in a chemical reaction. A
coefficient is placed in front of an element or compound if needed. If put in front of a compound the coefficient
effects each element in the compound.
If an element has a subscript, the coefficient is multiplied by the subscript to determine the total number of
atoms for that element.
Subscript: a number written to the lower right side of an element. It indicates the number of atoms of the
element that are present. CO2 O (Oxygen) has 2 atoms in this compound.