atoms ions and isotopes

Slide 1: 

Atoms, Ions and Isotopes

Protons Neutrons and Electrons : 

Protons Neutrons and Electrons

Atomic Number : 

Atomic Number Number of protons identifies an atom as a particular element Number of protons is called the Atomic Number All atoms of a particular element have the same atomic number.

Atomic # : 

Atomic # What is the atomic number of Gold? What element has 13 protons? Can Nitrogen have 8 protons?

Atomic # : 

Atomic # What is the atomic number of Gold? (79) What element has 13 protons? (Aluminum) Can Nitrogen have 8 protons? (no, only oxygen)

Atoms are Neutral : 

Atoms are Neutral How many protons does chlorine have? If all atoms are neutral and each proton is negative, how many electrons must chlorine have? How can you relate the number of protons to the number of electrons in an atom?

Ions : 

Ions Ions are atoms that have lost/gained electrons. Cations are ions that have lost electrons. Because they have lost negative electrons they are positive. Cats have paws, cations are positive!

Ions : 

Ions Ions are atoms that have lost/gained electrons. Anions are ions that have gained electrons. Because they have gained negative electrons, anions are negative.

Ions : 

Ions If a magnesium ion has a charge of +2, did the atom lose or gain electrons? How many electrons did it lose or gain? Is it a cation or anion?

Ions : 

Ions If a magnesium ion has a charge of +2, did the atom lose or gain electrons? (lost) How many electrons did it lose or gain? (2) Is it a cation or anion? (cation)

Ions : 

Ions If a nitrogen ion has a charge of 3-, has it lost or gained electrons? How many electrons did it lose or gain? Is it an anion or cation?

Ions : 

Ions If a nitrogen ion has a charge of 3-, has it lost or gained electrons? (gained) How many electrons did it lose or gain? (3) Is it an anion or cation? (anion)

Charge of an Ion : 

Charge of an Ion To find the charge of an ion, use the following equation: Charge = protons – electrons.

Writing nuclear symbols : 

Writing nuclear symbols Atoms can be represented by nuclear symbols Nuclear symbols also include Atomic Number B 5

Isotopes : 

Isotopes Isotopes are atoms that contain the same number of protons (same atomic #) but different number of neutrons. Ex. Chlorine can have 18 or 20 neutrons.

Mass Number : 

Mass Number Number of protons and neutrons gives an idea of the mass of an atom Number of protons AND neutrons is called the Mass Number Do not confuse Mass number with Average Atomic Mass. Mass number is NOT found on the periodic table. Average Atomic Mass

Mass Number : 

Mass Number Number of protons and neutrons gives an idea of the mass of an atom All atoms of a particular element have the same atomic number. Isotopes of the same element have different mass numbers. Average Atomic Mass

Writing nuclear symbols : 

Writing nuclear symbols Atoms can be represented by nuclear symbols Nuclear symbols also include Atomic Number Nuclear symbols also include Mass Number B 5 11

Nuclear Symbols : 

Nuclear Symbols Steps to writing nuclear symbol. Write the symbol of the element Write mass # on the top left. Write atomic # on the bottom left. If there is a charge, write the charge on the top right. Ex. 919F-1

Example : 

Example 919F-1 The atom above is fluorine which has an atomic number of 9, so it has 9 protons. To find the number of neutrons, subtract the atomic number from the mass number (19 - 9 = 10 neutrons) Since the charge is negative one, there must be one more electron than proton, so there must be 10 electrons.

Example : 

Example Write the nuclear symbol for an atom that contains 8 protons, 8 electrons, and 7 neutrons.

Example : 

Example Write the nuclear symbol for an atom that contains 8 protons, 8 electrons, and 7 neutrons. 15O 8 The atom is oxygen because there are 8 protons. 15 is the mass number you get by adding protons and neutrons. 8 is the atomic number, the number of protons. The charge is zero because protons minus electrons, 8-8, is zero.

Example : 

Example Write the nuclear symbol for an atom that contains 20 protons, 18 electrons, and 24 neutrons.

Example : 

Example Write the nuclear symbol for an atom that contains 20 protons, 18 electrons, and 24 neutrons. 44Ca+2 20 The atom is calcium because there are 20 protons. 44 is the mass number you get by adding protons and neutrons. 20 is the atomic number, the number of protons. The charge is +2 because protons minus electrons, 20-18 = +2.