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Chemistry Definitions
The text provides an overview of basic chemistry concepts, focusing on the composition and classification of matter. It explains how to determine the number of neutrons in an atom by subtracting the atomic number from the mass number.
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Chemistry Definitions Classification of Matter A flowchart with examples What the particles would look like Mixtures Can be separated by physical means Made up of more than one kind of molecule Heterogenous Mixture (mechanical mixture): A mixture where
more than one substance is visible. ex. compost Homogeneous Mixture (Solution): Particles mix well with each
other, so well that you can only see one phase or visible part. ex. salt mixed into water Compound: Pure substances that contain two or more
different elements formed for a chemical reaction Can be broken down by chemical means Made up of more than one kind of atom Element: Pure substances that can be broken down
into simpler substances Cannot be broken down by chemical means Made up of only one type of atom Pure substances: A substance that contains only one
type of particle Matter: Anything that has a mass and takes up space
(it has a volume) Molecules: Pure substances where the atoms combining
can be the same or different. ex. O2, H2O Bohr-Rutherford Diagram An example of what
the Bohr-Rutherford Diagram looks like On the energy levels, there are the electrons that orbit around the nucleus. 2 on the innermost shell (level) and 8 on all the others Each row (called periods on the periodic table) have the same number of energy levels as the number of row they're in Example: Period 1 (hydrogen and helium) have one energy level where the electrons orbit around the nucleus Energy levels are called shells Picture of definitions
on the periodic table Atomic Number The number of protons in the nucleus
(same number of electrons) Smaller of the two numbers Element Symbol The symbol used to identify an element
(eg. Co for Cobalt) Mass Number The mass of an atom of that element The bigger of the two numbers.
Used to find number of neutrons How To Get Mass Number Mass number = atomic number + number of neutrons How To Find Number Of
Protons, Neutrons, and Electrons Number of Electrons: same as number of protons Number Of Neutrons:
Atomic Mass subtracted by Atomic Number Number of Protons: Atomic number Hydrogen Grouped with alkali metals but
does not have the same properties Behaves like a non metal Metalloids Elements that posses both metal and nonmetal properties Found on the "staircase" Halogens Examples: Fluorine, Bromine, Chlorine Like to form salts Have 7 electrons in their outer orbit Most reactive nonmetals Occupy the 17th column Alkaline Earth Metals Examples: Magnesium, Calcium Barium React with acids Have two electrons in their outer orbit Reactive but not as reactive as alkali metals Occupy the 2nd column Alkali Metals Examples: Lithium, Potassium, Sodium Release hydrogen when mixed with water Have 1 electron in their outer orbit Are extremely reactive Occupy the 1st column Noble Gases Examples: Neon, Argon, Helium Don't form compounds Have a stable electron configuration (8 electrons) All are unreactive All gases are room temperature Found at the far right of the table Electrons Orbits around nucleus Almost 0 amu (atomic mass unit) Negative charge Protons Positive charge Neutrons How To Get Number Of Neutrons neutron number = mass - atomic number found in nucleus 1 amu (atomic mass unit) Neutral charge
