Chapter 18 Science Study Guide
Nitrogen has 5 valence electrons. How many does it need to have a full outer shell?
3 more
How many atoms total are in CH4
5
How many molecules are in 5H2O
5
Noble gases have how many valence electrons?
8
How many electrons does an atom want to have in its outer electron shell?
8 (or 2)
What is a coefficient?
A number placed in front of a chemical formula in an equation
What charge is the element that transfers the electron
After it transfers it becomes a cation (+)
What charge is the element who gets the transferred electron(s)
After the transfer it becomes a anion (-)
A chemical bond...
Can be ionic, covalent, or metallic; is an attraction between atoms that holds them together
A charged atom is called
An ion
A molecule that has a positive end and a negative end is a(n) __________________ molecule
Polar covalent
A element that loses electrons when bonding with other atoms has a _________ oxidation number
Positive
When writing the formula of a compound the symbol of the element with the ___________ oxidation number comes first.
Positive
A proton has a
Positive charge
When an atom loses one or more electrons it becomes
Positively charged (cation)
A compound that is composed of only two elements is a(n)
Binary
To form a molecule, atoms _____________electrons.
Share
The atoms in molecules are held together by
Sharing electrons; chemical bonds
A(n) ___________ is formed when atoms gain, lose, or share electrons.
chemical bond
CH4 is an example of a(n)
chemical formula; molecule
What is in a covalent?
two nonmetals
A chemical bond is made up of matter. (True or false)
False it creates matter
In ionic bonds, valence electrons are
Transferred from one atom to another; gained or lost by atoms
How many atoms are needed to form a molecule
Two or more
How many nitrogen atoms are there in NH3
1
______________ have properties unlike their elements
Compounds
A bond that forms betweeen atoms when they share electrons is a(n) __________ bond.
Covalent
A(n) _________ tells what elements make up a compound and the ratios of the atoms of those elements.
Formula
What is an example of a covalent
H+H+O— H2O
In a chemical formula what does the subscript tell you?
How many atoms of an element are in a unit of a compound
compounds containing polyatomic ions have both...
Ionic and covalent bonds
An atom is "happiest" when
It has a full outer (valence) shell
Neutral particles formed as a result of covalent bonding are called
Molecules
When two or more atoms are covalently bonded together, we call that a(n)
Molecules
An example of a ionic
Na+Cl— NaCl
When an atom gains one or more electrons it becomes
Negativity charged (anion)
Molecules that do not have oppositely charged ends are ______________ molecules
Non-polar
What does a Covalent do?
They share
What does a ionic do?
They take electrons, transfer
Why do atoms share electrons
To have full outer electron shells
What does "Covalent" mean?
Together valences; Valence electrons are shared
A(n) ___________ is a compound that has water chemically attached to its ions.
hydrate
An atom that has gained or lost electrons is called a(n)
ion
The force of attraction between the opposite charges of the ions in an ionic compound is a(n)
ionic bonding
What is in a ionic?
metal and non metal
An electron has a
negative charge
A neutron has a
neutral charge
An ionic bond is the attraction between
oppositely charged ions
A positive or negative number that is assigned to an element to show its combining ability in a compound is a(n)
oxidation number
A group of atoms with a positive or negative charge is a(n)
polyatomic ion
An atom is _________ when its outer energy level is filled with electrons
stable
