Basic Chemistry Review for test
Download
Report
Transcript Basic Chemistry Review for test
The basic unit of all matter
Small in size
Proton
Neutron
Electron
Proton and Neutron – NUCLEUS of the atom
(center)
Electrons – found rapidly moving in energy
levels (energy clouds)
Proton = Positive (+)
Neutron = Neutral (0)
Electron = Negative (e-)
Proton
Neutron
Remember – the electrons are SOOOO LIGHT
that they are not part of the mass (atomic
weight)
There is an equal number of protons and
electrons
If there are more protons – then the atom
would have an overall POSITIVE charge
If there are more electrons – then the atom
would have an overall NEGATIVE charge
Use the terms
◦ Symbol
◦ Atomic Weight (Mass)
◦ Atomic Number
A
Atomic Number
Symbol
Atomic Weight
(mass)
Hydrogen
Oxygen
Nitrogen
Carbon
There is also phosphorus and sulfur, but I
only want you to focus on the four listed
above.
The symbol for Krypton is
The mass number for Calcium is
The atomic number for Beryllium is
The symbol for Krypton is
Kr
The mass number for Calcium is
The atomic number for Beryllium is 4
The number of molecules present
LARGE NUMBER written before the element
symbol
Ex: 4CO2
There are 4 molecules of carbon dioxide
The number of atoms present
SMALL NUMBER written within the chemical
formula
Ex: 4CO2
There are 8 atoms of oxygen
Remember to distribute (4 x 2=8)
5C2H4
How many molecules are present?
How many atoms of Carbon are present?
How many atoms of Hydrogen are present?
How many TOTAL atoms are present?
5C2H4
How many molecules are present? 5
How many atoms of Carbon are present?
10 (5x2 – remember to distribute)
How many atoms of Hydrogen are present?
20 (5x4 – remember to distribute)
How many TOTAL atoms are present?
30 (distribute and then add up)
(5x2) = 10
(5x4) = 20
10 + 20 = 30
A. Electrons
B. Protons
C. Neutrons
D. Valence Electrons
A. Electrons
B. Protons
C. Neutrons
D. Valence Electrons
Choice D is the most accurate answer here
A.
B.
C.
Gained
Lost
Shared
A.
B.
C.
Gained
Lost
Shared
In the outermost energy level of an atom
8 electrons!
8 – OCTET rule
◦ The outermost energy level will be complete when it
contains 8 electrons.
◦ Atoms will gain/lose/share electrons to reach this
stability!
****EXCEPTION****
◦ Hydrogen and Helium follow the DUET RULE (can
only have 2 electrons in the outermost shell to be
stable and unreactive)
A.
B.
C.
D.
Carbon
Neon
Helium
Magnesium
A.
B.
C.
D.
Carbon – 4 opportunities to bond (vacancies)
Neon
Helium
Magnesium – 6 opportunities to bond
(vancancies)
Neon is stable because it is a noble gas – already
has 8 electrons
Helium is stable because it is also a noble gas –
but follows duet rule so it has 2 electrons
Single Bond
Double Bond
Triple Bond
Single Bond
◦ Atoms share 2 electrons (1 pair)
Double Bond
◦ Atoms share 4 electrons (2 pairs)
Triple Bond
◦ Atoms share 6 electrons (3 pairs)
Types of Elements
Number of atoms
Location of atoms
Example –
1 Oxygen
2 Hydrogen
COVALENT BONDS
SHARING OF ATOMS!!
Phosphorus
Hydrogen
Nitrogen
Oxygen
Phosphorus
Hydrogen
Nitrogen
Oxygen
WATER
Changes or transforms one set of chemicals
into another
CHANGES to the BONDS – breaking and
reforming bonds
Reactants
Products
Reactants
◦ ENTER into a chemical reaction (before the arrow)
Products
◦ PRODUCED by a chemical reaction (after the arrow)
Reactants
Products
Coefficients
Subscripts
C - Reactants
D - Products
A - Coefficients
B – Subscripts
Reactants REACTto produce PRODUCTS
Matter cannot be created nor destroyed
Arrangement of atoms is what is changed
Reactants must equal products
Na + Cl2 NaCl
ANSWER - NO
2Na + Cl2 2NaCl