Chemical Nomenclature

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Chemical Nomenclature

Covalent Compounds

Common Names

These are covalent compounds that are frequently referred to by common names rather than scientific ones.

Special Cases

Diatomics

These elements do not exist as single atoms. they are gases which always appear as a pair of atoms when they're naturally occurring.

Turning Formulas Into Words

Just follow the prefixes (no crisscross, no canceling)

Naming Covalent Compounds

when naming covalent compounds you use a prefix for each atom, this tells us the number of atoms in the molecule. the ending of the second atom is changed to "ide"

Prefixes 1) mono 2) di 3) tri 4) tetra 5) penta 6) hexa 7) hepta 8) octa 9) nona 10) deca

These are all placed before each atom to indicate the number of atoms in the molecule

UNLESS the first atom in the equation is only ONE you dont set the prefix as "mono" you just leave it as it is. EX:

None metals combine through covalent bonds. non-metals want to gain electrons because they almost have a full valence shell. If two non metals want to gain this can be accomplished through sharing electrons this is called a COVALENT BOND

ex: water (H2O) - both elements are non-metals (hydrogen and oxygen) - both want to gain electrons not lose Hydrogen only needs to gain one electron to fill its valence shell oxygen only needs 2 more electrons to fill its outer shell

They can both achieve full valence shells by SHARING their electrons this is allowed because the electrons being shared belong to both of them at the same time

Formulas

Crisscross Method

Reducing in Ionic Compound Formulas

The formulas of ionic compounds can be reduced.

If there is a common between the amount of ions you divide it by the GCF (greatest common factor) In this case the GCF is 2

Subscripts were divided by 2

This is a method for creating the formulas for ionic compounds.

Get the two ions you're dealing with, ex:

cross the charges. Although the metal stays first in the equation. (if the charge is 1, it does not need to be shown in the formula)

Formulas are written through the atomic symbols. The number of each atom required to make that compound is represented through a subscript of a number beside that symbol. Metal always comes first.

Example:

Ionic Compounds

When a metal ion and non-metal ion come together to form an ionic bond. The metal will give its electrons to the non metal. Meaning the metal is positively charged (cation) because it loses electrons, and the non-metal is negatively charged (anion), because it gains electrons.

The attraction between the positive and negative charges create the ionic bond. (called electrostatic attraction)

Naming in Ionic Compounds

1) Name the metal (cation) 2) Name the non-metal (anion) 3) Change the ending of the non-metal to "ide"

EX:

1) Aluminum 2) Aluminum Oxygen 3) Aluminum Oxide

The overall charge of Ionic Compounds

Ionic Compounds have a net overall charge of ZERO

This means the total positive charge + total negative charge = 0

This can be put into an equation:

Figuring out which ionic charge of the multivalent metal for an equation

ex: FeO

In this ex we need to determine the charge of the Iron Ion Since we know the overall charge of an Ionic Compound is zero we can create an equation to find the unknown value by subbing in the charge of an Oxygen Ion (-2)

let X represent the unknown charge (iron)

Binary Ionic Compounds

A binary ionic compound is composed of ions of two different elements - one of which is a metal, and the other a nonmetal.

MultiValent Metals In Ionic Compounds

When naming ionic compound formulas with multivalent metals, you must indicate which ionic charge it is with roman numerals

Metals that have multiple ionic charges:

Some Examples:

Fixed Valence Metals In Ionic Compounds

Fixed valence metals in ionic compounds are metals that have one ionic charge

Lithium is a fixed Valence Metal meaning its only ionic charge is Li+1

Ionic Compounds with radicals (polyatomic)

2 or more atoms that are contently bonded together and have an overall charge

Naming with Polyatomic Ions

1) Name the Metal (unless NH3 is in the equation, then that is named first because it is a cation) 2) Name the Polyatomic Cation the ending does not need to be changed (unless the equation is NH3 followed by a non metal)

ex: Mg (OH)2 1) Magnesium 2) Magnesium Hydroxide

Formulas with Polyatomic Ions

You place brackets around the polyatomic ion if there is more than one

This is important because it indicates in the example above that there are 2 hydroxide ions. Without it would appear there are 2 hydrogen ions ** Brackets should only be used if there is MORE THAN ONE polyatomic ion