Unit B Matter and Chemical Change: Section 3.0 Flashcards
What is a chemical formula?
A combination of symbols that we use to identify an element or a compound
What does a chemical formula identify?
The elements in the compound and the amount of each element
Why did they create a system to name chemicals?
Because different scientists called compounds and elements different things and it caused great confusion, especially across languages.
Who created a naming system for chemicals?
Guyton du Morveau
What did Guyton du Morveau decide when naming compounds?
Always put the metal elements first
What does IUPAC stand for?
International union of pure and of applied chemistry
What does IUPAC do?
They determine the appropriate name for each chemical
What suffix do ionic chemical compounds always end with?
-ide
What does the subscript of a chemical formula represent?
the amount of atoms that are present
What does no subscript indicate within a chemical formula?
Only one atom is present
How do you indicate the state of a formula?
By putting a s/l/g in brackets as a subscript.
You can also show aqueous with aq
What does the subscript (aq) indicate?
That the compound is dissolved in water
How many electrons can fit in the first shell of an atom?
2
How many electrons can fit in the second shell of an atom?
8
How many electrons can fit in the third shell of an atom?
8 or 18
What is an ionic compound?
Pure substances formed as a result of the attraction between particles of the opposite charges called ions.
Formed from a metal and a nonmetal.
what is an ion?
An atom that has become electrically charged because it has lost or gained an electron or electrons.
What is a positive ion?
an ion that has lost one or more electrons
Electrons are negatively charged.
What is a negative ion?
An ion that has gained one or more electrons.
What are polyatomic ions?
A group of atoms acting as one.
Ionic compounds can form between a metal and a nonmetal but can also form between a metal and a polyatomic ion, or a polyatomic ion and a nonmetal. You can even form them using two different polyatomic ions.
What are the properties of Ionic compounds?
Ions -Have high melting points -Are good conductors -Have distinct crystal shape -Are solids at room temperature
What do ions form when they combine?
Ionic compounds
These are crystals like table salt NaCl (sodium chloride)
Where do you write the ionic charge in an ionic compound formula?
As a superscript after each ion.
Na+Cl-
Na+(OH)- (lye = sodium hydroxide)
Ca2+Cl-
When should you use roman numerals when writing the ion charge?
When the element has more than one common ion charge in order to specify which one it has in that specific case.
The Roman numeral will only be used when listing the ionic compound in words. Do not use a Roman numeral when only one charge was possible.
Copper (I) sulfide is
Cu+S2-
What are the first 10 roman numerals?
1 = I 2 = II 3 = III 4 =IV 5 = V 6 = VI 7 = VII 8 = VIII 9 = IX 10 = X
What are oxyanions?
Polyatomic anions containing oxygen
What is formed when non-metals combine?
A pure substance called a molecular compound containing covalent bonds. Can also be called a covalent compound.
Sharing of electrons
What are the properties of molecular compounds?
- They can be any state at room temperature
- They tend to be poor conductors but are good insulators
- low melting and boiling points in comparison to ionic compounds
Is there an ion charge when writing molecular compounds? How do you know how many atoms are present within the molecular compound?
No, since molecular compounds do not contain ions.
Look at the name to know how many atoms there are of each element. The prefixes State the quantity of atoms. If there is no prefix, then it means one.
In the chemical formula you can look at the subscript to the right of the element to know the quantity of that element.
What is the exception when writing molecular compounds?
All can be named using scientific names except ones containing hydrogen
For example H2S is named as an acid. Do not name it like a covalent compound or molecule.
What are the prefixes when writing molecular compounds?
- mono
- di
- tri
- tetra
- penta
- hexa
- hepta
- octa
- nona and ennea
- deca
