chem exam 2 - unit 5 nomenclature

elements and molecular elements

diatomic molecules

molecular compounds

covalent compounds

ionic compounds (charged particles, cations, and anions)

• type-1 binary ionic compounds

• type-2 binary ionic compounds

• polyatomic ionic compounds

acids

• binary acids

• oxy acids

nomenclature

a system or a process to assign very specific and particular scientific names to the chemical compounds according to its structure, properties

nomenclature rules allow chemists all over the world to use the same __ when referring to compounds

terminology

why do we need nomenclature?

• to avoid any overlapping and confusion

• helps with assigning proper classification

name rules for an element with a single atom?

keeps the name indicated in the periodic table (can possibly add the word atom)

name rules for an element that has two of the same kind of atoms

keeps the same name as in the periodic table with the added word molecular (to show that it is a molecule)

• ex: molecular bromine, molecular iodine

how many elements are naturally occuring?

92

how many elements are synthetic, artificial, or created in labs through nuclear reactions?

26

what atoms are molecular compounds made up of?

nonmetal + nonmetal

• neutral molecules (no charge)

• they share electrons to form molecular bonds

what atoms are ionic compounds made up of?

metal + nonmetal

how to name molecular compounds

1. write the name of the first atom that appears in the chemical formula

2. add a prefix (di-, tri-, etc.) to indicate the number of atoms of the element in the compound

3. write the second atom’s name and alter it to add the suffix -ide to the root

4. add a prefix (di-,tri-, etc.) to indicate the number of atoms of the element in the compound

ex: P2O5 and CH4 —> DiPhosporous pentoxide Carbon tetra hydride

prefixes and subscripts:

1 mono-

2 di-

3 tri-

4 tetra-

5 penta-

6 hexa-

7 hepta-

8 octa-

9 nona-

10 deca-

element names used for the 2nd element in a covalent compound

hydrogen → hydride

carbon → carbide

nitrogen → nitride

oxygen → oxide

phosphorus → phosphide

sulphur → sulphide

fluorine → fluoride

chlorine → chloride

iodine → iodide

naming molecular compounds (Two nonmetals)

1. write the name of the first element and add the prefix if needed

2. write the second atom’s name and convert it using the suffix -ide

3. add prefix if needed to it

ex: CO2 is carbon dioxide

the number of atoms in the chemical formula indicated by a subscript

• ex: N2O4, NO, NO3, N2O5)

NO: nitrogen oxide

NO3: nitrogen trioxide

N2O5: dinitrogen pentoxide

Type-1 ionic compounds are made from which groups in the periodic table?

group-1A, 2A, and 3A

Type-2 ionic compounds are made from which groups in the periodic table?

• transition metals

• nonmetals

how are ionic bonds formed?

by transfer of electrons between the atoms

ionic compounds are __ particles

charged

type-1 binary ionic compounds are formed when?

when group-1A, 2A, and 3A metals combine with non-metals

rules for naming type-1 binary ionic compounds

1. start by naming the atoms that appears first in the formula (always a metal) by using their name in the periodic table

2. name the second atom (always a nonmetal) and change it by adding the suffix -ide to its root

• NOTE: prefixes are NOT used when naming ionic compounds (ONLY used with covalent compounds)

EX: MgBr2 → Magnesium Bromide

converting chemical name to chemical formula with type-1 binary ionic compounds:

1. identify the metal and nonmetal

2. find the charges on both the atoms using the periodic table

3. crisscross the numbers (ignore signs)

4. use them as subscripts

5. simplify if needed (if they have a common factor)

ex: Magnesium Chloride

step 1: Mg,Cl

step 2: charges

Mg = +2

Cl = -1

Step 3: criss cross

Mg+2 Cl-1 → Mg1Cl2

ex: Aluminum Fluoride

Al = +3

F = -1

crisscross → Al1F3 → AlF3

ex: Calcium Oxide

Ca = +2

O = -2

crisscross → Ca2O2 → Ca2O2 → simplify → CaO

Type-2 ionic compounds are indicated with the __ __ in the compound’s name

Roman numerals

• these indicate the element’s positive charge

Polyatomic Ionic Compounds

• consist of more than one type of atom

• atoms in a polyatomic ion are usually covalently bonded to one another, so they stay together as a single charged unit

ex: NO3- = nitrate

rules for naming polyatomic ionic compound

1. the cation is written first in the name, and the anion is written second

2. if formula has 2+ of the same polyatomic ion, put the ion in parentheses, with the number outside of it

1. identify the cation (positive ion) first

• if it is a metal with a fixed charge (like Na+, Ca2+) just use its name

• if it is a transition metal, determine its charge and write it as a Roman numeral

2. identify the anion (negative ion)

• if it is a polyatomic ion (N³-), use its ion name (like nitrate, sulfate, etc.)

• do NOT change the ending to -ide if it is polyatomic

ex: Ca(NO₃)₂

• Ca²+ = calcium

• NO₃⁻ = nitrate

name = calcium nitrate

ex: Fe(NO₃)₃

1. Fe = Iron (a transition metal)

2. NO₃⁻ = Nitrate (charge = –1)

3. There are 3 NO₃⁻, so total negative charge = –3

4. That means Fe must be +3 to balance.

name: Iron(III) nitrate

converting name to formula with polyatomic ionic compounds

steps:

1. write the symbols of cation and anion

2. determine charges of each ion

3. use crisscross method to balance charges

4. use parenthesis around poly ion if u need more than one of it

Ammonium phosphate

1. Ammonium = NH₄⁺

2. Phosphate = PO₄³⁻

3. Crisscross: NH₄⁺ (1) and PO₄³⁻ (3) → need 3 ammonium ions to balance 1 phosphate.

✅ Formula: (NH₄)₃PO₄

rule naming polyatomic ionic compounds

1. write the name of cation (no prefix)

2. write the name of anion from polyatomic chart (no prefix)

naming acids

• if name or formula starts with hydrogen —> its an acid

acids are categorized into two groups:

• binary acids: those containing only hydrogen and a nonmetal ex: HCI)

• oxy-acids: those containing hydrogen, a nonmetal part includes oxygen ex: HNO3)

naming binary acids

• composed of hydrogen and a nonmetal

(name format: hydro)+(base name of nonmetal + -ic)+acid

ex: HCI(aq) is hydrochloric acid

naming oxyacids

1. omit “hydrogen”

2. start with the root name of the anion

3. replace “-ate” with “-ic” , or “-ite” with “-ous”

4. add “Acid” at the end

ex: H2CO3 —> carbonic acid