Molecules and Compounds CH5 Flashcards

Questions and Answers

What is the definition of a subscript in a chemical formula?

Number written below line in a chemical formula.

What does the subscript number do in a chemical formula?

That number multiplies the preceding atom or the preceding package wrapped in parentheses.

What is the formula for water?

H2O

What are Diatomic Elements?

Elements that exist in nature as pairs. Signup and view all the answers

List the seven diatomic elements.

H2, N2, O2, F2, Cl2, Br2, I2 Signup and view all the answers

What is a mnemonic sentence to memorize the seven diatomic elements?

Horses Need Oats For Clear Brown Eyes. Signup and view all the answers

What is another mnemonic to memorize the seven diatomic elements?

Have No Fear Of Ice Cold Beer. Signup and view all the answers

Most of the diatomic elements reside in either Group _____ and/or in the second period.

VIIA Signup and view all the answers

When do you use the diatomic form of an element?

When the element is a reactant or formed product. Signup and view all the answers

In the reaction H2 + O2 → H2O, why does water not get a '2' subscript after the oxygen symbol?

H2O is a compound. Signup and view all the answers

In the reaction 2 Na + 2 H2O → 2 NaOH + H2, why must hydrogen appear in diatomic form?

Hydrogen is a formed product. Signup and view all the answers

What does the Latin word 'nomen' mean?

Name Signup and view all the answers

What is the purpose of nomenclature in chemistry?

To provide unique names for each and every chemical. Signup and view all the answers

Why do we need a systematic naming system?

There are over 23 million compounds plus more discovered every day. Signup and view all the answers

What are the different nomenclature systems in place for ionic and covalent compounds?

Ionic compounds have different properties than covalent compounds. Signup and view all the answers

What holds atoms together?

Bonds Signup and view all the answers

What is an ionic bond?

Electrostatic attraction of two ions due to oppositely charged particles. Signup and view all the answers

What is a covalent (molecular) bond?

Attraction through sharing of electrons. Signup and view all the answers

What makes hydrogen an odd element?

It has both metal and nonmetal properties. Signup and view all the answers

How should hydrogen be considered for predicting bond types?

As a nonmetal. Signup and view all the answers

What is the classification of CO2?

Covalent. Signup and view all the answers

What is the classification of NaCl?

Ionic. Signup and view all the answers

What type of bond is PbBr2 an example of?

Ionic. Signup and view all the answers

What is the classification of H2S?

Covalent. Signup and view all the answers

What is a monatomic ion?

When a single atom becomes an ion. Signup and view all the answers

What is a polyatomic ion?

A cluster of two or more atoms covalently bonded together but possessing an overall charge. Signup and view all the answers

What does NaCl consist of?

Na+ + Cl-; each is a monatomic ion. Signup and view all the answers

What does NaNO3 consist of?

Na+ + NO3-; nitrate is a polyatomic ion. Signup and view all the answers

What is an ion?

Electrically charged particle resulting from loss or gain of electron(s). Signup and view all the answers

How to calculate ion charge? Group 'A' Roman Numerals indicate _________ of outer electrons.

number Signup and view all the answers

What is the octet rule?

Atoms tend to undergo reactions that result in an outer electron configuration of the nearest noble gas. Signup and view all the answers

How does the octet rule work?

<ol> <li>Find the elemental symbol on a PT; 2) Advance box-by-box to the nearest Group VIIIA element.</li> </ol> Signup and view all the answers

What is the ionic charge of potassium ion?

K+1 Signup and view all the answers

What is the ionic charge of aluminum ion?

Al 3+ Signup and view all the answers

What is the ionic charge of oxide ion?

O 2- Signup and view all the answers

What is the ionic charge of bromide ion?

Br -1 Signup and view all the answers

What does the periodic table indicate about the ionic charge of many 'A' group elements?

It provides information about their common ionic charges. Signup and view all the answers

What is ionic nomenclature?

Two-part name: metal ion and nonmetal ion. Signup and view all the answers

What is an example of how different compounds must have unique names?

CuCl vs CuCl2 Signup and view all the answers

What is the naming order for ionic compounds?

Name the cation first, the anion second. Signup and view all the answers

How do you name a cation?

Use the name of the element. Signup and view all the answers

How do you name an anion?

Use the name of the element, cut off its tail, then add IDE ending. Signup and view all the answers

What is Table salt's name?

Sodium chloride. Signup and view all the answers

What is the compound MgO named?

Magnesium oxide. Signup and view all the answers

How would you name CaS?

Calcium sulfide. Signup and view all the answers

What is most notable about transition metals and their charges?

They are stable at several possible cationic charges. Signup and view all the answers

What is the Stock System used for?

It uses Roman Numerals to indicate charges of cations. Signup and view all the answers

What do the Roman Numerals indicate in ionic naming?

Charge of cation. Signup and view all the answers

Give an example of metals that have more than one possible charge.

Fe+3 and Fe+2; Cu+2 and Cu+1. Signup and view all the answers

How would you name CuCl?

Copper(I) chloride. Signup and view all the answers

How would you name CuCl2?

Copper(II) chloride. Signup and view all the answers

How would you name FeBr2?

Iron(II) bromide. Signup and view all the answers

How would you name FeBr3?

Iron(III) bromide. Signup and view all the answers

What does the OLD SYSTEM indicate?

ic > ous; cation with higher charge gets IC suffix. Signup and view all the answers

What is an example of the OLD SYSTEM?

Cu+2 cupric > Cu+1 cuprous. Signup and view all the answers

What is a problem with the OLD SYSTEM?

You need to know Latin; need to know both possible charges. Signup and view all the answers

Why do we still use the OLD System?

Common names still appear in hospital settings. Signup and view all the answers

When to use Roman Numerals in naming?

When dealing with Danger Zone cations. Signup and view all the answers

When encountering Danger Zone cations, how do you determine the cation charge?

Use your anion knowledge to back out the cation charge. Signup and view all the answers

What must ionic compounds be?

Electrically neutral. Signup and view all the answers

What is the charge of the cation when naming CuI2?

Copper must be +2. Signup and view all the answers

How do you name Fe2O3?

Iron(III) oxide. Signup and view all the answers

What is a classic error when naming Fe2O3?

Naming it iron(II) oxide. Signup and view all the answers

When should Roman Numerals not be used in ionic naming?

Unless the cation is in the Danger Zone. Signup and view all the answers

What is the name of PbS2?

Lead(IV) sulfide. Signup and view all the answers

What is the name of Ba3P2?

Barium phosphide. Signup and view all the answers

How do you name CoBr3?

Cobalt(III) bromide. Signup and view all the answers

What are polyatomic ions?

A unit of covalently bonded atoms carrying a net ionic charge. Signup and view all the answers

What is sulfate?

SO4-2. Signup and view all the answers

When comparing similar polyatomic ions, what does 'ate' indicate?

'Ate' indicates more oxygen while 'ite' indicates less oxygen. Signup and view all the answers

What is the difference between sulfate and sulfite?

Sulfate is SO4 2- while sulfite is SO3 2. Signup and view all the answers

What does the other part of a polyatomic name come from?

From the central nonmetal atom. Signup and view all the answers

What does the IDE ending usually indicate?

An element has become anion; not a polyatomic. Signup and view all the answers

What is an exception to the IDE ending rule?

Hydroxide (OH-1) is a polyatomic even though it ends in IDE. Signup and view all the answers

How would you name CaCO3?

Calcium carbonate. Signup and view all the answers

What is the name of Na2CrO4?

Sodium chromate. Signup and view all the answers

What is the purpose of parentheses in polyatomic formulas?

Must use ( ) when there is more than one of a particular polyatomic. Signup and view all the answers

How does Ca(OH)2 demonstrate the use of parentheses?

It indicates there is more than one hydroxide. Signup and view all the answers

How would you name NH4NO3?

Ammonium nitrate. Signup and view all the answers

What does (NH4)2S show regarding clarity in formulas?

Parentheses clarify the composition of the ion. Signup and view all the answers

Study Notes

Chemical Nomenclature and Compounds

Subscript: A number written below the chemical formula line, indicating the quantity of the preceding atom or grouped atoms in parentheses.
H2O: Represents water, a simple yet essential compound in chemistry.
Diatomic Elements: Elements that naturally occur in pairs, requiring a "2" subscript (e.g., H2, N2).
Seven Diatomic Elements: H2, N2, O2, F2, Cl2, Br2, I2.
Mnemonic for Diatomic Elements: "Horses Need Oats For Clear Brown Eyes" or "Have No Fear Of Ice Cold Beer".
Diatomic Form Usage: Used when the element is a reactant or product, not in compounds.

Ionic and Covalent Bonds

Bond Types: Atoms are held together by bonds; types include ionic (attraction between charged ions) and covalent (sharing of electrons).
Ionic Bonds: Formed between metals and nonmetals due to electrostatic attraction.
Covalent Bonds: Occur between nonmetals through shared electrons.

Ionic and Polyatomic Ions

Ionic Charge Calculation: Determined using Group "A" Roman Numerals indicating outer electrons.
Octet Rule: Atoms react to achieve a stable electron configuration similar to the nearest Noble Gas (8 electrons). Helium is stable with 2.
Monatomic Ion: A single atom ionized through loss or gain of electrons.
Polyatomic Ion: A group of two or more atoms covalently bonded, carrying an overall charge. Examples include Na+ and NO3- (nitrate).

Naming Ionic Compounds

Ionic Nomenclature: Involves names for both the cation (positive ion) and anion (negative ion).
Naming Protocol: Cation names precede anions; cations retain their names, while anions receive an "ide" ending.
Roman Numerals in Nomenclature: Used for cations with multiple charges, indicating their respective charges, e.g., Cu(I) and Cu(II).

Common Charges and Examples

Common Cation Charges: K+ (potassium), Al3+ (aluminum), O2- (oxide), Br- (bromide).
Compound Examples:
- NaCl: sodium chloride (ionic).
- MgO: magnesium oxide (ionic).
- CO2: carbon dioxide (covalent).
- H2S: hydrogen sulfide (covalent).

Naming Conventions and Polyatomics

Polyatomic Ion Identification: Names will often include "ate" for more oxygen and "ite" for less oxygen, e.g., SO4^2- (sulfate) versus SO3^2- (sulfite).
Exceptions for IDE Endings: Anions typically receive "ide," but hydroxide (OH-) remains a polyatomic ion.

Clarification through Parentheses

Use of Parentheses: Necessary when multiple instances of a polyatomic ion are in a formula to prevent confusion, e.g., Ca(OH)2 denotes two hydroxide ions.

Additional Notes

Unique Names for Compounds: Each compound must have a distinct name.
Importance of Nomenclature: Systematic naming assists in understanding compound properties based on their classification.

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Test your knowledge of molecules and chemical nomenclature with these flashcards. Each card presents key terms and their definitions, helping you understand important concepts such as subscripts and chemical formulas. Ideal for students studying chemistry concepts in Chapter 5.