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Chemistry Mrs. h
all chemistry
Question | Answer |
---|---|
Protons are found in the | nucleus and have a positive charge |
Electrons are found | orbiting the nucleus and have a negative charge |
Neutrons are found in the | nucleus and have a neutral charge |
Nucleus holds | the protons and the neutrons |
Energy levels orbit | around the nucleus. |
Energy levels may also be called | Electron Cloud or Electron Shells |
The first level can hold | 2 electrons |
The 2nd level can hold | 8 electrons |
The 3rd level can hold | 8 electrons |
Happy Atoms are | 2, 8, 8 |
Atomic Mass (amu) is made up | of protons and neutrons |
To find the Atomic Mass | add protons plus neutrons |
1 proton = | 1amu |
1 neutron = | 1amu |
A = P = E | Atomic # = # of Protons = # of Electrons |
M-A=N | Atomic Mass – Atomic # = # of Neutrons |
Atomic # + # of Neutrons = | Atomic Mass |
Valence Electrons are | The electrons that farthest away from the nucleus |
The number of valance electrons can range from | 1 to 8. |
The columns on the periodic table | are called groups 1 – 18 |
Groups are | Also called families |
Groups refers to the number of | valence electrons (the number in the 1’s place tells you this) |
Elements in each group all have | similar properties |
Valence Electrons determine the | chemical properties of the element (how reactive) |
The rows on the periodic table are called | periods 1 – 7 |
Periods | Tells you the number of energy levels or electron shells |
Dmitri Mendeleev is credited with | the creation of the 1st periodic table. He increasing atomic mass. |
Dmitri Mendeleev was able to | predict that there would be at least three more elements and he was able to predict were they would be on the table. |
Modern periodic tables are arranged by | Atomic Number. |
Group 1 – are the most | reactive. They have one valence electron and they are NOT happy. The one valence electron really wants to leave. |
Group 18 – Noble Gases; have a | full outer shell of valence electrons, so they don’t bond with any other elements; completely un-reactive and the most stable; |
All atoms are | neutral unless they gain or lose an electron. |
When an atom gains an electron, the atom goes from having | a neutral charge to having a negative charge. It is called a negative ion. |
When an atom loses an electron, the atom goes from having a neutral charge | to having a positive chare. It is called a positive ion. |
A chemical formula is a shorthand notation that uses | chemical symbols and number to represent a substance. |
A chemical formula shows how many of each kind | of atom are present in a molecule. |
Each capital letter represents | a new element (some have a lower case letter with it) |
To determine the number of elements in a compound, | count the number of capital letters. |
SUBSCRIPTS only refer | to the atom that they are BEHIND of. |
COEFFICIENTS apply to the | entire compound. You MULTIPLY the coefficients and SUBSCRIPTS. |
If elements or compounds are inside of PARENTHESES, then the SUBSCRIPTS behind the parentheses | applies to everything inside. |
Balanced equations are | equations that have the same number of each kind of atom on both sides of the equation; |
the mass of the reactants equals | the mass of the products |
The Law of Conservation of Matter says | that matter can neither be created or destroyed, but can be changed in form. |
Physical Properties are | A characteristic of a substance that can be observed without changing the substances composition of matter. |
Physical Changes are | A change that alters the form or appearance of a material but does not make the material into a new substance. |
Physical Changes | occur when objects undergo a change that does not change their chemical nature. |
A chemical property is | Any characteristic that is observed when a substance interacts with another substance. |
Burning or flammability is | a chemical property. |
Rusting is a | chemical property. |
Tarnishing is a | chemical property. |
Chemical change or chemical reaction is | a change in matter that forms a new substance and energy is either given off or absorbed. |
In a chemical change | elements may combine to form compounds, or compounds may be broken down into elements, or compounds may change into other compound. |
A chemical change produces | a new substance with properties different from the original substances. |
Signs of a chemical change include | signs of an energy change (heat, light, sound), change in color, gas formation (bubbles), solid formation (precipitate), and reaction to oxygen. |