Question

name: teacher: date: q2 chemistry: u4l8 intro to covalent bonding prework part 2: naming and writing formulas for covalent compounds directions: read the passage below. as you read, annotate the important information and vocabulary words. then answer the questions. part 1: read & annotate: covalent compounds form when two nonmetals share electrons. since multiple combinations are possible, we use prefixes to tell us how many atoms of each element are in the compound. note: never use mono- on the first element if there’s only one atom. steps to name a covalent compound example: co₂ 1. name the first element. → carbon 2. name the second element with a prefix and change the ending to -ide. - there are 2 oxygen atoms → prefix di- - change oxygen to oxide 3. put it all together: → carbon dioxide you try: pcl₅ 1. first element name: 2. 5 chlorine atoms = prefix - & change chlorine to → 3. put it all together: steps to write the formula from the name (do not simply the formula!) example: dinitrogen tetroxide 1. first element: dinitrogen = n₂ 2. second element: tetroxide = o₄ 3. final formula: n₂o₄ you try: sulfur hexafluoride 1. sulfur = 2. hexafluoride = 3. final formula: part 2: draw a line to match the formulas with their names. co n₂o₄ *sf₆ ch₄ pcl₅ carbon tetrahydride dinitrogen tetroxide carbon monoxide phosphorus pentachloride sulfur hexafluoride part 3: true or false 1. mono- is always used on the first element. 2. covalent compounds only form between nonmetals. 3. the name \tetrahydride\ would indicate 4 hydrogen atoms. 4. co is named carbon monoxide, not monocarbon monoxide. 5. p₂o₅ is called diphosphate pentoxide. 6. covalent compounds are usually formed between a metal and a nonmetal. 7. the formula for nitrogen trifluoride is nf₃.

Explanation:

Step1: Solve "You Try: PCl₅"

Step 1.1: First element name

The first element in \( \text{PCl}_5 \) is phosphorus (P), so the first element name is Phosphorus.

Step 1.2: Prefix for 5 chlorine atoms and change to -ide

From the prefix table, 5 atoms correspond to "penta-". Chlorine changes to chloride (by changing the ending to -ide). So the prefix is penta- and the second element part is chloride.

Step 1.3: Put it all together

Combine the first element (Phosphorus) and the second element with prefix (penta - chloride). So it is Phosphorus pentachloride.

Step2: Solve "You Try: Sulfur hexafluoride"

Step 2.1: Sulfur formula

Sulfur is represented as \( \text{S} \) (since there is no prefix, it means 1 atom, so \( \text{S} \)).

Step 2.2: Hexafluoride formula

"Hexa-" means 6, and fluoride is \( \text{F} \), so hexafluoride is \( \text{F}_6 \).

Step 2.3: Final formula

Combine sulfur (\( \text{S} \)) and hexafluoride (\( \text{F}_6 \)) to get \( \text{SF}_6 \).

Step3: Solve "Part 2: Match formulas with names"

• \( \text{CO} \): Carbon has 1 atom (no prefix), oxygen has 1 atom (prefix mono - ). So it is carbon monoxide (matches "carbon monoxide").
• \( \text{N}_2\text{O}_4 \): Nitrogen has 2 atoms (di - ), oxygen has 4 atoms (tetra - ), so it is dinitrogen tetroxide (matches "dinitrogen tetroxide").
• \( \text{SF}_6 \): Sulfur (S) and fluorine with 6 atoms (hexa - ), so it is sulfur hexafluoride (matches "sulfur hexafluoride").
• \( \text{CH}_4 \): Carbon (C) and hydrogen with 4 atoms (tetra - ), so it is carbon tetrahydride (matches "carbon tetrahydride").
• \( \text{PCl}_5 \): Phosphorus (P) and chlorine with 5 atoms (penta - ), so it is phosphorus pentachloride (matches "phosphorus pentachloride").

Step4: Solve "Part 3: True or False"

Step 4.1: Mono - is always used on the first element.

From the note: "Never use mono - on the first element if there's only one atom." So this statement is False.

Step 4.2: Covalent compounds only form between nonmetals.

The passage says "Covalent compounds form when two nonmetals share electrons", so covalent compounds form between nonmetals. This statement is True.

Step 4.3: The name "tetrahydride" would indicate 4 hydrogen atoms.

" Tetra - " means 4, so tetrahydride indicates 4 hydrogen atoms. This statement is True.

Step 4.4: CO is named carbon monoxide, not monocarbon monoxide.

From the note: "Never use mono - on the first element if there's only one atom." So CO is named carbon monoxide (not monocarbon monoxide). This statement is True.

Step 4.5: \( \text{P}_2\text{O}_5 \) is called diphosphate pentoxide.

The correct naming: Phosphorus (P) has 2 atoms (di - ), oxygen has 5 atoms (penta - ). So it should be diphosphorus pentoxide, not diphosphate pentoxide. This statement is False.

Step 4.6: Covalent compounds are usually formed between a metal and a nonmetal.

Covalent compounds form between nonmetals, ionic compounds form between metal and nonmetal. So this statement is False.

Step 4.7: The formula for nitrogen trifluoride is \( \text{NF}_3 \).

Nitrogen (N) has 1 atom (no prefix), fluorine has 3 atoms (tri - ), so the formula is \( \text{NF}_3 \). This statement is True.

Answer:

You Try: PCl₅

1. First element name: \(\boldsymbol{\text{Phosphorus}}\)
2. 5 chlorine atoms = prefix \(\boldsymbol{\text{penta-}}\) & change chlorine to \(\boldsymbol{\text{chloride}}\)
3. Put it all together: \(\boldsymbol{\text{Phosphorus pentachloride}}\)

You Try: Sulfur hexafluoride

1. Sulfur = \(\boldsymbol{\text{S}}\)
2. Hexafluoride = \(\boldsymbol{\text{F}_6}\)
3. Final formula: \(\boldsymbol{\text{SF}_6}\)

Part 2: Match formulas with names

• \(\text{CO}\) —— carbon monoxide
• \(\text{N}_2\text{O}_4\) —— dinitrogen tetroxide
• \(\text{SF}_6\) —— sulfur hexafluoride
• \(\text{CH}_4\) —— carbon tetrahydride
• \(\text{PCl}_5\) —— phosphorus pentachloride

Part 3: True or False

1. \(\boldsymbol{\text{False}}\)
2. \(\boldsymbol{\text{True}}\)
3. \(\boldsymbol{\text{True}}\)
4. \(\boldsymbol{\text{True}}\)
5. \(\boldsymbol{\text{False}}\)
6. \(\boldsymbol{\text{False}}\)
7. \(\boldsymbol{\text{True}}\)