## How do we map matter (atomic structure)?

State the position of protons, neutrons, and electrons in the atom:
In the core of the atom are protons and neutrons, which make up the nucleus. The nucleus is surrounded by electrons. Protons are charged favorably. There is a negative charge on electrons.

Define the terms mass number and atomic number:
Atomic number:
The chemical element’s atomic number or proton number is the number of protons present in the nucleus of each atom of that element. A proton, located in the nucleus of an atom, is a positively charged particle.

Atomic Mass:
The number of masses also called the number of atomic masses or the number of nucleons is the number of protons and neutrons in the nucleus of the atom. That is exactly equal to the atomic mass of an atom expressed in units of atomic mass.

State the relative masses & relative charges of the subatomic particles:

Determine valency of electrons using electronic structure
By deciding the electronic configurations of elements, Valence electrons can be detected. The total number of valence electrons in that part is subsequently given by the number of electrons in the outermost shell.

Evaluate the models for atomic theory
John Dalton:
Dalton’s model was based on Ancient Greek ideas of Atoms. The greek word for atom being “aternone” meaning invisible. Although it introduced the concept of an atom being a sphere, it did not take the subatomic particles into consideration

J.J. Thomson:
J.J. is most commonly known for his discovery of electrons in 1897. With this discovery, he created the ‘plum pudding’ model, in which it shows a series of scattered electrons in a cloud of protons. This was the first model to take electrons into account, but had no account for neutrons

Ernest Rutherford
After experiments of firing positively charged particles in a sheet of gold. Through analyzing the deflection, it was discovered that atoms are mostly made of empty space with a positive charge in the nucleus

Niels Bohr:
Bohr took Rutherford’s model and made it so that the electrons exist solely within certain orbits around a positively charged nucleus. This is the most commonly-used model used today

Erwin Schrodinger:
Schrodinger took quantum physics into the model of an atom, in which electrons do not move in paths, rather in waves. It is impossible to pinpoint the exact location of an electron, thus there are clouds of the probability of where an electron might be.

Define the term ‘isotope’
An Ion, is any atom or set of atoms containing one or more electrical charges which are positive or negative. Positively charged ions are known as cations; anions are negatively charged ions. Ions are formed by inserting or withdrawing electrons from neutral atoms or molecules or other ions; by mixing ions with other particles; or by splitting a covalent bond between two atoms in such a manner that all of the bond’s electrons are left in conjunction with one of the previously bound atoms.

There are two types of ions :

Cations (positive)

Anions (negative)

Outline examples & uses of isotopes:
The elements all contain isotopes. Two major forms of isotopes exist stable and unstable (radioactive). 254 known stable isotopes are present. Both artificial (lab-made) isotopes are unstable and thus radioactive; they are called radioisotopes by researchers. One or two isotopes of an element are typically the most stable and widespread. Generally different isotopes of an atom have the same physical and chemical properties. That’s because they have the same proton and electron numbers.

Calculate the relative atomic mass of element using the percentage abundance of its isotopes
Change each percent abundance into decimal form by dividing by 100. Multiply this value by the atomic mass of that isotope. Add together for each isotope to get the average atomic mass.

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