Unit 1 - Foundations of Chemistry - Chapter 1 - Atomic ...palmarin.weebly.com/uploads/2/3/0/7/23075168/chapter_1_-_atomic... · Chapter 1 - Atomic Structure and Nomenclature ... Chemistry

Unit 1 - Foundations of ChemistryChapter 1 - Atomic Structure and Nomenclature

Watch: “An Introduction to Chemistry”

Mr. Palmarin Chapter 1 - Nomenclature 1 / 47

https://www.youtube.com/watch?v=izeuGr0lbN0

Section 1.1 - Introduction to Chemistry

What is Chemistry?

Chemistry is the study of the properties of materials and the changes thatmaterials undergo.


Why study Chemistry?

It is the central science, leading to a fundamental understanding of othersciences and technologies.

It is an extremely practical science that greatly impacts our daily living:

improvement to health care

conservation of natural resources

protection of the environment

provision of our everyday needs for food, clothing, and shelter

Using chemistry, we have discovered helpful pharmaceutical chemicals,increased food production, and developed plastics.


Classifications of Matter

Matter is the physical material of the universe. We can classify matter inthe following ways:


Classifications of Matter

The tremendous variety of matter in our world is due to the combinationsof only about 100 very basic substances called elements.

Chemistry attempts to understand the properties of matter in terms ofatoms.

Summary:

All matter is composed of elements.

All elements are composed of very small particles called atoms.

What are atoms made up of?


Atomic structure:

Atoms contain two main regions called the nucleus and the electroncloud.The nucleus is composed of two subatomic particles called protonsand neutrons.The electron cloud is composed of one subatomic particle called theelectron.

(a) The Bohr Model - aconvenient model that accuratelypredicts how atoms will behave

(b) The Electron Cloud Model - thismodel most accurately reflectsreality


Pure Substances

A pure substance is matter that has distinct properties and acomposition that doesn’t vary from sample to sample.

Examples:

Water

Oxygen

Table salt

All substances are either elements or compounds.

Elements are composed of only one kind of atom (ex: O, H, Fe).

Compounds are substances composed of two or more elements(water, table salt).


A molecule is essentially a group of atoms bonded together.

Note: Molecules of elements consist of two or more similar atoms.Molecules of compounds consist of two or more different atoms.

Figure: Brown et al; Chemistry: The Central Science; p. 8


Section 1.2 - The Periodic Table

Periodic Table - A structured arrangement of elements that allows us toexplain and predict physical and chemical properties.

Note: You can print off a copy of the periodic table and a sheet ofcommon ions from the Moodle.


Symbols on the Periodic Table


Charges

The charges of the three key subatomic particles:

Protons - Positively charged. Denoted: p+

Neutrons - Neutrally charged. Denoted: n0

Electrons - Negatively charged. Denoted: e–

Elements on the Periodic Table are in electronically neutral form; i.e.they carry no charge. To be electronically neutral, an atom must have anequal number of protons and electrons.

Example: Which atom below is electronically neutral?


Ions

The nucleus of an atom is unchanged by chemical processes, but atomscan readily gain or lose electrons.

An ion is formed when electrons are removed from or added to a neutralatom.

An anion is a negatively charged ion. A cation is a positively charged ion.

Example: How many electrons does Na+ have?


Practice: How many electrons does Cl– have? What type of ion is Cl– ?


Predicting Ionic Charges

General rule: Metal atoms tend to lose electrons to form cations,whereas nonmetal atoms tend to gain electrons to form anions.

Figure: The red line divides metals from nonmetals. It also separates cations fromanions.


How Elements Form Compounds

Much of chemical activity involves the transfer of electrons from onesubstance to another.

Ionic compounds are generally combinations of metals and nonmetals.These compounds are held together by attractions between oppositecharged ions (like a magnetic attraction). This is called an ionic bond.

Molecular compounds are generally composed of nonmetals only.Electrons are shared between atoms. This is called a covalent bond.

Examples:

1 MgCl2 (magnesium chloride)

2 H2O (water)



Homonuclear Molecules

These are molecules composed of only one type of element.

The most common are:

P4 S8 H2 O2 F2 Br2 I2 N2 Cl2

Acronym: PS HOFBrINCl

For example: Why would two chlorine atoms share a pair ofelectrons to form a covalent bond?

Notice how they both have 7 electrons in their outer orbit (valence shell).If they both gain 1 electron, they will be stable (8 outer electrons is ideal).


Polyatomic Ions

Polyatomic ions - groups of atoms that tend to stay together and carryan overall ionic charge.

Examples:

nitrate - NO –3

hydroxide - OH–

bicarbonate - HCO –3

chlorate - ClO –3

sulfate - SO 2–4

phosphate - PO 3–4


Note: You can print off a copy of the periodic table and a sheet ofcommon ions from the Moodle.


Section 1.3 - Naming Ionic Compounds

Steps for naming binary ionic compounds:

1 Name the metal (cation) first.

2 Name the nonmetal (anion) second. For the nonmetal, drop theending and add “ide”.

3 Use Roman Numerals in parentheses to indicate which charge of themetal is used. This is only used for metals that make more than onecharge.


Examples:

1) Ca3N2 → calcium nitride

2) Mg3P2 → magnesium phospide

3) Al2O3 → aluminum oxide

4) CuCl2Look on your periodic table. Notice how copper makes more than onecharge (2+ or 1+). Recall how compounds are electronically neutral.Since chlorine always makes a 1− charge (and there are two chlorineatoms), this implies that copper must be taking a 2+ charge in thissituation. → copper (II) chloride

5) FeBr3 Similar to 4) → iron (III) bromide

6) CoN

N takes 3− and we have one nitrogen and one cobalt atom. Cobalt istaking a 3+ to make the compound neutral → cobalt (III) nitride


Practice: Name the following compounds. [See Section 1.3 Video]

1) CaCl2

2) MgBr2

3) FeI3

4) CuCl2

5) Cr3N2

6) BeO


Steps for naming ionic compounds with polyatomic ions:

1 For polyatomic compounds, name the metal first followed by thename of the polyatomic ion. The endings do not change. Don’tforget about metals that make more than one charge.

Examples:

1) Al(OH)3

The OH compound is called “hydroxide” (see the back of your periodictable - your sheet of polyatomic ions).

Therefore → aluminum hydroxide

2) NaHCO3 Similar to 1) → sodium bicarbonate

3) Sn(NO3)4

NO3 is called nitrite. But notice how Sn (tin) takes two charges (2+ or4+). Therefore, we need to use roman numerals. Nitrite takes a 1−charge; therefore, tin is taking a 4+ charge in this situation.

→ tin (IV) nitrite


Practice: Name the following compounds. [See Section 1.3 Video]

1) KNO3

2) Mg3(PO4)2

3) NaOH

4) Pb(NO2)4


Writing Formulas for Ionic Compounds

Steps:

1 Write the ionic charges above the symbols.

2 Determine the lowest number of each element that would make theentire compound electronically neutral.

i.e. “Crisscross” the numbers, using them as subscripts. Rememberto reduce when appropriate.

Key fact: The sum of the charges on the positive ions equals the sum ofthe charges on the negative ions.


Examples:

1) calcium iodide

Step 1: Ca2+ I–

Step 2: We need exactly 2 iodine atoms to cancel out calcium’s 2+charge → CaI2

Note: Crisscrossing the charges would have given the same result.Here, no reducing is necessary.

2) sodium phosphide

=⇒ Na+ P3– (we need 3 sodiums to cancel out phosphorus’ 3-charge) → Na3P

3) calcium chloride

=⇒ CaCl2


Practice: Write the formulas for the following compounds.[See Section 1.3 Video]

1) sodium bromide

2) strontium nitride

3) potassium phosphide

4) magnesium nitride

5) zinc iodide


Note: Some metals can make more than one kind of ion. Romannumerals in brackets indicate the charge of the ion (not how many are inthe formula). On your periodic table (if you printed in colour), thecommon charges are listed in red.

Examples:

1) iron (III) oxide

Step 1: Fe3+ O2–

Step 2: Here, we need exactly 2 Fe atoms and 3 O atoms to arrive atan electronically neutral compound → Fe2O3

2) iron (II) oxide

Step 1: Fe2+ O2–

Step 2: Here, we need exactly 1 Fe atom and 1 O atom to arrive at anelectronically neutral compound → FeO

Note: If you are using the crisscross method you must reduce thenumbers; i.e. Fe2O2 reduces to FeO.



1) cobalt (II) chloride

2) nickel (III) oxide

3) lead (IV) selenide

4) tin (II) nitride

5) iron (III) phosphide


Note: Ionic compounds may include polyatomic ions. Reference the “Listof Polyatomic Ions” to determine the charges of the polyatomic ions.

Remember to put the entire polyatomic ion in brackets if you need morethan one!

Examples:

1) sodium carbonite

Step 1: Na+ CO 2–2

Step 2: We need exactly 2 Na atoms and 1 CO2 molecules to arrive atan electronically neutral compound → Na2CO2

2) aluminum sulfate

Step 1: Al3+ SO 2–4

Step 2: We need exactly 2 Al atoms and 3 SO4 molecules to arrive atan electronically neutral compound → Al2(SO4)3

Note: Brackets are used to indicate that there are 3 SO4 molecules.



1) sodium chlorate

2) magnesium phosphate

3) silver nitrate

4) barium sulfite

5) iron (II) nitrite


Section 1.4 - Molecular Compounds

Molecular compound - formed when nonmetals (anions) share electronswith other nonmetals (anions).

Covalent bond - a shared pair of electrons held between two nonmetalatoms that holds the atoms together.


Writing Formulas for Molecular Compounds

Steps:

1 Write the symbols of each nonmetal.

2 Write the appropriate subscripts for each nonmetal that correspondsto the prefixes used.

Note: The prefix “mono” is never used on the first nonmetal.

mono di tri tetra penta hexa hepta octa nona deca

1 2 3 4 5 6 7 8 9 10

Note: This list will not be given to you on the exam(s). Either commit tomemory, or write this on the top of your periodic table.


Examples: Write the formulas for the following molecular compounds.

1) carbon dioxide

No prefix in front of “carbon” implies there is one carbon. The prefix“di” implies there are two oxygen atoms. → CO2

2) dinitrogen trioxide → N2O3

3) carbon tetrafluoride → CF4


Practice: Write the formulas for the following molecular compounds.[See Section 1.4 Video]

1) dihydrogen monoxide

2) diboron trioxide

3) phosphorus trihydride


Writing Names for Molecular Compounds

Steps:

1 Write the name of the first nonmental and then the second.

2 Place the appropriate prefixes in front of each of the names. Theprefixes correspond to the subscripts of each element.

3 Drop the ending of the last element named and add -ide.

Note: Sometimes prefixes are shortened when the ending vowel of theprefix “conflicts” with a starting vowel in the compound. This makes thename easier to pronounce.

For example: “tetraoxide” is typically written as “tetroxide” or“monooxide” is shortened to “monoxide”.


Examples: Name the following molecular compounds.

1) CS2 → carbon disulfide

Recall: The prefix “mono” is never used for the first element.

2) N2O4 → dinitrogen tetroxide

Recall: tetraoxide is shortened to tetroxide. This avoids two vowelsbeing next to each other.

3) P4S10 → tetraphosphorus decasulfide

Practice: Name the following molecular compounds.[See Section 1.4 Video]

1) CO

2) CF4

3) C2H6


Section 1.5 - Acids

An acid is a substance whose molecules yield hydrogen ions (H+) whendissolved in water. An acid is composed of H+ ions connected to an anion(negative ion). The number of H+ ions is equal to the charge of the anion.

Example: SO 2–4 requires two H+ ions =⇒ H2SO4

H2SO4 is called sulfuric acid. Note: acids always start with H bonded toan anion.

How do we name acids?


There are three kinds of acids:

Type 1: Acids containing anions whose names end in -ide arenamed by changing the -ide ending to -ic, adding theprefix hydro- to this anion name, and then followingwith the word “acid”.

Examples:

1) HCl

Notice hydrogen is out front (therefore this is an acid) and how theanion (chloride) ends in “ide”. Therefore, this is a Type 1 acid =⇒replace “ide” with “ic” and add the word “acid” → hydrochloric acid

2) H2S

This is an acid. Here, the anion is sulfide. Now, this will not turn intosulfic acid. There are two exceptions (sulfur and phosphorus). Inthese examples, we will add a vowel (this is definitely strange, but it’ssimply the convention). → hydrosulfuric acid


Type 2: Anions that end in -ate are named by changing -ateto -ic and then adding the word “acid”.

Type 3: Anions that end in -ite are named by changing -ite to-ous and then adding the word “acid”.

Phrase: ate - ic; ite - ous

Examples:

1) HClO3

Reference your list polyatomic ions. ClO3 is chlorate. Therefore, ate ischanged to “ic”. → chloric acid

2) H2SO4 → sulfuric acid

3) HNO2 → nitrous acid

4) H3PO4 → phosphoric acid

Recall: Here was the second except; i.e. we add an extra vowel.


Practice: Name the following acids. [See Section 1.5 Video]

1) HI

2) HIO3

3) HIO2

4) H3P

5) H3PO3


Writing Formulas for Acids

Steps:

1 Use the same criss-cross method as with ionic compounds.

2 H+ will always be at the start of your criss-cross.

Note: The number of hydrogens out front will always be equal to thecharge of the anion (negative ion).


Examples:

1) hydrosulfuric acid

“Hydro” implies type 1 =⇒ ic - ide and we’re dealing with sulfur;S2– . Therefore, we require 2 H atoms to balance S’s charge of 2−

→ H2S

2) carbonic acid

No “hydro” and ends in “ic” =⇒ type 2. Therefore, ic - ate. Sowe’re dealing with carbonate; CO 2–

3 and so once again we will need 2H’s to balance the charge. → H2CO3

3) nitrous acid

No “hydro” and ends in “ous” =⇒ type 3. Therefore, ous - ite.Nitrite is NO –

2 and so we only need 1 H to balance that charge.→ HNO2


Practice: Write formulas for the following acids.[See Section 1.5 Video]

1) chromic acid

2) carbonous acid

3) hydrochloric acid

4) oxalic acid

5) hydrocyanic acid


Section 1.6 - Basic Organic Naming

An organic compound is a compound that contains carbon. We will beusing some basic organic compounds throughout the semester. Thesecompounds will either be alkanes or alkenes.

Alkane: Consist only of hydrogen and carbon. General formula: CnH2n+2;i.e. all bonds are single bonds and each carbon atom is saturated withhydrogen.

Ex: CH4, C2H6, C3H8, ...

Alkene: Consist of exactly two carbons less than its corresponding alkane.General formula: CnH2n; i.e. there exists one double bonded carbon tocarbon.

Ex: C2H4, C3H6, C4H8, ...


The organic naming system uses the following prefixes to identify thenumber of carbons. The ending ane or ene identifies the number ofhydrogens (single bonds vs. double bond).

meth eth prop but pent hex hept oct non dec

1 2 3 4 5 6 7 8 9 10

Examples: Name the following alkanes/alkenes.

1) C4H10

4 carbons =⇒ “but”. Is this “ane” or “ene”? 10 hydrogens comesfrom 2(4) + 2; i.e. 2n + 2 were n is the number of carbon atoms.2n + 2 =⇒ alkane. → butane

2) C8H16 16 H’s =⇒ 2(8); i.e. 2n =⇒ alkene → octene

3) C6H18 → hexane

4) C8H18 (commonly called gasoline) → octane


Practice: Name or write the formula for the following organic compounds.[See Section 1.6 Video]

1) C2H4

2) propane

3) C4H8

4) pentene

5) decane


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Unit 1 - Foundations of Chemistry - Chapter 1 - Atomic ...palmarin.weebly.com/uploads/2/3/0/7/23075168/chapter_1_-_atomic... · Chapter 1 - Atomic Structure and Nomenclature ... Chemistry