Intro to Chemistry Study Guide: Periodic Table, Compounds, and Reactions

Q1. Based on the general trends in the periodic table, circle the element in each of the following pairs that has the most metallic character:

Background

Topic: Periodic Table Trends

This question tests your understanding of metallic character, which increases as you move down a group and decreases as you move across a period from left to right.

Key Terms:

• Metallic character: The tendency of an element to lose electrons and form positive ions (cations).

• Periodic trends: Patterns in properties of elements across periods and groups.

Step-by-Step Guidance

1. Identify the position of each element in the pair on the periodic table.

2. Recall that metallic character increases as you move down a group and decreases as you move from left to right across a period.

3. Compare the elements in each pair based on their group and period placement.

4. Determine which element is further down and/or further to the left on the periodic table.

Try solving on your own before revealing the answer!

Final Answer:

The element that is lower and further left in each pair has the most metallic character.

For example, between sodium (Na) and magnesium (Mg), Na is more metallic.

Q2. State the number of valence electrons for each of the following elements.

Background

Topic: Electron Configuration and Valence Electrons

This question tests your ability to determine the number of valence electrons based on an element's group number in the periodic table.

Key Terms:

• Valence electrons: Electrons in the outermost shell of an atom, important for chemical bonding.

• Group number: For main-group elements, the group number indicates the number of valence electrons.

Step-by-Step Guidance

1. Locate the element on the periodic table.

2. Identify its group number (for main-group elements, this is usually 1A–8A).

3. For main-group elements, the group number corresponds to the number of valence electrons.

4. Write down the number of valence electrons for each element.

Try solving on your own before revealing the answer!

Final Answer:

For example, carbon (C) in group 4A has 4 valence electrons.

Q3. According to general trends in the periodic table, circle the element in each of the following pairs that has the larger atomic radius.

Background

Topic: Atomic Radius Trends

This question tests your understanding of how atomic radius changes across periods and down groups in the periodic table.

Key Terms:

• Atomic radius: The distance from the nucleus to the outermost electron shell.

• Periodic trends: Atomic radius increases down a group and decreases across a period from left to right.

Step-by-Step Guidance

1. Identify the elements in each pair and their positions on the periodic table.

2. Recall that atomic radius increases as you move down a group and decreases as you move across a period.

3. Compare the elements based on their group and period placement.

4. Determine which element is lower in the group or further left in the period.

Try solving on your own before revealing the answer!

Final Answer:

The element that is lower in the group or further left in the period has the larger atomic radius.

Q4. Draw the electron dot formula for each of the following elements.

Background

Topic: Lewis Dot Structures

This question tests your ability to represent valence electrons as dots around the element symbol.

Key Terms:

• Electron dot formula (Lewis dot structure): Shows the valence electrons as dots around the element symbol.

• Valence electrons: Electrons in the outermost shell.

Step-by-Step Guidance

1. Determine the number of valence electrons for the element (see Q2).

2. Write the element symbol.

3. Place dots around the symbol to represent each valence electron (up to 8).

4. Arrange the dots in pairs on each side of the symbol.

Try solving on your own before revealing the answer!

Final Answer:

For example, oxygen (O) has 6 valence electrons, so its dot structure is O with 6 dots around it.

Q5. Refer to the periodic table and circle the element in each of the following pairs that has the higher ionization energy.

Background

Topic: Ionization Energy Trends

This question tests your understanding of how ionization energy changes across periods and down groups.

Key Terms:

• Ionization energy: The energy required to remove an electron from an atom.

• Periodic trends: Ionization energy increases across a period and decreases down a group.

Step-by-Step Guidance

1. Identify the elements in each pair and their positions on the periodic table.

2. Recall that ionization energy increases as you move from left to right across a period and decreases as you move down a group.

3. Compare the elements based on their group and period placement.

4. Determine which element is higher in the group or further right in the period.

Try solving on your own before revealing the answer!

Final Answer:

The element that is higher in the group or further right in the period has the higher ionization energy.

Q6. Refer to the periodic table and write the complete electron configuration for each of the following ions.

Background

Topic: Electron Configuration of Ions

This question tests your ability to write electron configurations for ions, which involves adding or removing electrons based on the ion's charge.

Key Terms and Formula:

• Electron configuration: The arrangement of electrons in an atom or ion.

• Ion: An atom with a positive (cation) or negative (anion) charge.

• For cations, remove electrons from the highest energy level; for anions, add electrons.

Step-by-Step Guidance

1. Identify the neutral atom's electron configuration.

2. Determine the charge of the ion and whether electrons are added or removed.

3. Adjust the electron configuration accordingly.

4. Write out the full electron configuration for the ion.

Try solving on your own before revealing the answer!

Final Answer:

For example, Na+ has the electron configuration of neon (1s2 2s2 2p6).

Q7. Provide the chemical formula for each of the following compounds:

Background

Topic: Chemical Formulas for Compounds

This question tests your ability to write chemical formulas based on the names of compounds, including polyatomic ions.

Key Terms:

• Chemical formula: Representation of a compound using element symbols and subscripts.

• Polyatomic ions: Ions composed of multiple atoms (see tables for common ions).

Step-by-Step Guidance

1. Identify the cation and anion in the compound.

2. Determine their charges and balance them to form a neutral compound.

3. Write the formula using the correct subscripts for each ion.

4. Double-check the charges to ensure neutrality.

Try solving on your own before revealing the answer!

Final Answer:

For example, sodium carbonate is Na2CO3.

Q8. Provide the chemical formula for each of the acids:

Background

Topic: Chemical Formulas for Acids

This question tests your ability to write formulas for acids based on their names, using knowledge of polyatomic ions and acid naming conventions.

Key Terms:

• Acid: A compound that releases H+ ions in solution.

• Polyatomic ions: Used in naming and writing formulas for acids (see tables).

Step-by-Step Guidance

1. Identify the root name of the acid and the corresponding polyatomic ion.

2. Recall naming rules: "-ate" becomes "-ic acid", "-ite" becomes "-ous acid".

3. Write the formula by combining H+ with the polyatomic ion, balancing charges.

4. Double-check the formula for correct subscripts and charge neutrality.

Try solving on your own before revealing the answer!

Final Answer:

For example, sulfuric acid is H2SO4.

Q9. Supply a systematic name for each of the following compounds:

Background

Topic: Nomenclature of Compounds

This question tests your ability to name compounds systematically, including ionic and molecular compounds.

Key Terms:

• Systematic name: The official IUPAC name for a compound.

• Nomenclature rules: Naming conventions for ionic and molecular compounds.

Step-by-Step Guidance

1. Identify the type of compound (ionic or molecular).

2. For ionic compounds, name the cation first, then the anion (use "-ide" for simple anions).

3. For molecular compounds, use prefixes to indicate the number of atoms.

4. Apply the correct naming rules for each compound.

Try solving on your own before revealing the answer!

Final Answer:

For example, NaCl is sodium chloride.

Q10. Classify each of the following reactions:

Background

Topic: Types of Chemical Reactions

This question tests your ability to identify reaction types such as synthesis, decomposition, single replacement, double replacement, and combustion.

Key Terms:

• Synthesis: Two or more substances combine to form one product.

• Decomposition: One substance breaks down into two or more products.

• Single replacement: One element replaces another in a compound.

• Double replacement: Two compounds exchange ions.

• Combustion: A substance reacts with oxygen, producing energy.

Step-by-Step Guidance

1. Examine the reactants and products in each equation.

2. Identify the pattern of change (combination, breakdown, exchange, etc.).

3. Match the pattern to the reaction type.

4. Label each reaction accordingly.

Try solving on your own before revealing the answer!

Final Answer:

For example, 2H2 + O2 → 2H2O is a synthesis reaction.

Q11. Complete and balance each equation. If no reaction (no precipitation) occurs, write “NR”

Background

Topic: Balancing Chemical Equations and Precipitation Reactions

This question tests your ability to balance chemical equations and predict whether a reaction occurs based on solubility rules.

Key Terms and Formula:

• Balancing equations: Ensuring the same number of atoms of each element on both sides.

• Precipitation reaction: Formation of an insoluble product (precipitate) in solution.

• Solubility rules: Guidelines for predicting whether a compound is soluble or insoluble in water.

Step-by-Step Guidance

1. Write the reactants and predict the products based on reaction type.

2. Use solubility rules to determine if a precipitate forms.

3. If a precipitate forms, write the product and balance the equation.

4. If no precipitate forms, write "NR" for no reaction.

Try solving on your own before revealing the answer!

Final Answer:

For example, mixing NaCl and AgNO3 forms AgCl (precipitate) and NaNO3 (soluble).

Q12. Predict whether or not a reaction occurs for each of the following:

Background

Topic: Predicting Chemical Reactions

This question tests your ability to use solubility rules and activity series to predict if a reaction will occur.

Key Terms:

• Solubility rules: Used to predict precipitation reactions.

• Activity series: Used to predict single replacement reactions.

Step-by-Step Guidance

1. Identify the type of reaction (precipitation or single replacement).

2. Use solubility rules to check if a precipitate forms.

3. Use the activity series to check if a metal can replace another in a compound.

4. Predict whether a reaction occurs based on these rules.

Try solving on your own before revealing the answer!

Final Answer:

If a precipitate forms or a metal is more active than another, a reaction occurs.

Q13. Predict which of the following metals reacts with water at room temperature.

Background

Topic: Reactivity of Metals

This question tests your understanding of the activity series and which metals react with water to release hydrogen gas.

Key Terms:

• Activity series: A list of metals ranked by their reactivity.

• Active metals: Metals that react with water at room temperature.

Step-by-Step Guidance

1. Refer to the activity series provided.

2. Identify which metals are listed as reacting with water at room temperature.

3. Compare the metals in the question to the list.

4. Circle those that are active enough to react with water.

Try solving on your own before revealing the answer!

Final Answer:

Li, K, Ba, Sr, Ca, and Na react with water at room temperature.

Q14. State whether the following compounds are soluble or insoluble in water.

Background

Topic: Solubility Rules

This question tests your ability to use solubility rules to determine if a compound dissolves in water.

Key Terms:

• Solubility: The ability of a substance to dissolve in water.

• Solubility rules: Guidelines for predicting solubility of ionic compounds.

Step-by-Step Guidance

1. Identify the ions present in the compound.

2. Refer to the solubility rules table to check if the compound is generally soluble or insoluble.

3. Look for any exceptions listed in the rules.

4. State whether the compound is soluble or insoluble based on the rules.

Try solving on your own before revealing the answer!

Final Answer:

For example, NaCl is soluble, while AgCl is insoluble.

Q15. Complete and balance each of the following neutralization reactions.

Background

Topic: Neutralization Reactions

This question tests your ability to write and balance equations for reactions between acids and bases, forming water and a salt.

Key Terms and Formula:

• Neutralization reaction: Acid + base → water + salt.

• Balancing equations: Ensuring equal numbers of atoms on both sides.

Step-by-Step Guidance

1. Write the reactants: an acid and a base.

2. Predict the products: water and a salt.

3. Write the formula for the salt based on the cation from the base and the anion from the acid.

4. Balance the equation for atoms and charge.

Try solving on your own before revealing the answer!

Final Answer:

For example, HCl + NaOH → NaCl + H2O.