Atomic Structure

Housekeeping… Need Music Requests for your test or you get my choice Need a gatekeeper for each class Definition of explode - a violent release of energy resulting from a rapid chemical or nuclear reaction, esp one that produces a shock wave, loud noise, heat, and light.

Objectives: Determine how many of each subatomic particle are in an atom Use an element tag to determine subatomic particles in atoms

Matter and Atoms Matter describes everything that has mass and takes up space What is not matter? Black holes have mass, but don’t take up space Antimatter has mass, it just has an opposite spin to its counterpart

Atoms and Elements An atom is the smallest unit of matter An element is the simplest form of a substance that cannot be broken down by chemical means What is the difference?

What is a subatomic particle? Subatomic means “smaller than an atom” The three subatomic particles are Protons Neutrons electrons

Locations Subatomic particles are either inside the nucleus, or outside of it Outside of the nucleus is referred to the electron cloud, where the electrons are found The protons and neutrons are found inside the nucleus

The electron cloud Electrons move around the nucleus and have different energy levels Electrons have less energy the closer they are to the nucleus

Modern model Shows an electron cloud rather than individual electrons outside of the nucleus Denser areas of the cloud mean a higher probability of electrons

Energy in the cloud Each energy level can hold a certain number of electrons each shell but the first will fill to 8 before a new shell is made 8 is great!!! 1st shell – 2 2nd shell – 8 3rd shell - 18

Electrical Charge Electrical charges can be positive or negative Protons are positively charged Electrons are negatively charged Neutrons have no electrical charge, they are referred to as neutral

Electrical Charges ctd. An atom usually has an equal number of positively charged protons and negatively charged electrons This makes an atom electrically neutral

Atomic number The atomic number is the large number within the element tag on the periodic table The atomic number tells you how many protons are in one atom of that element Protons determine an element’s identity So, in a neutral atom, the atomic number tells you how many protons and electrons are in an atom - APE

Mass Number The more protons and neutrons an atom has, the greater its mass The total number of protons and neutrons in an atom is called its mass number Electrons are left out of the calculation of the mass number because they add so little mass to an atom

Average atomic mass Most atoms exist in a number of different forms, called isotopes Each form has the same number of protons, but a different number of neutrons Isotopes have different physical properties but their chemical properties are the same

Determining numbers of neutrons The average atomic mass of the elements are found as a decimal number on the periodic table This number can be rounded to a whole number, then you subtract the atomic number (number of protons) and you are left with the neutrons of the atom – M-A=N