NAME: BLOCK: DATE: CHEMISTRY: COUNTING ATOMS IN COMPOUNDS WORKSHEET #7.0.1 INSTRUCTIONS: Write the quantity of atoms of each element opposite the formula of the compound for the quantity of formula units and molecules shown: For example: SP,0, P= (5×2 =) 10 0= (5×3 =15 For example: 4Zn(NO) Zn-4×1 =)4 N-(4x1x2-)8 0-4×3 x 2 = ) 24 4K.CO K- O 25r(PO4)2 Sra P= 3. 3N010 NE O= 4. N) N N- 5. 8CI:O CI- 0 = 6. Ca(CHO) Ca H 7. 12NaBr Na Br= 8. 4AKOH), Al O 9. 3NaHCO3 Na H- 10. 5Gas(Cr:0) Ga Cr 7C2S2 C= S- 12. 4Fe 0 Fe O 13. 6Ba(MnO4)2 Bar Mn 14. 3V.Os V 0= 15. 2KNO: K- N- O 16. Mg – S 0 17. 9MgSO 5A1:(SiOs) Al- 4A (10) Au Si O- 18. I= O= (Continued)
The Correct Answer and Explanation is :
To answer this worksheet, we need to count the number of atoms of each element in the given chemical compounds based on the quantity of formula units or molecules stated. Let’s break down the process step-by-step, using the first example provided as a guide.
Example Breakdown:
The compound is 4Zn(NO₃)₂:
- Zn (Zinc): We have 4 formula units of Zn(NO₃)₂. Since each unit contains 1 Zn atom, we multiply 4 by 1 to get 4 Zn atoms.
- N (Nitrogen): In one formula unit of Zn(NO₃)₂, there are 2 Nitrogen atoms because the subscript is 2. So, we multiply 4 by 2 (for the 4 formula units) to get 8 Nitrogen atoms.
- O (Oxygen): In one unit of Zn(NO₃)₂, there are 3 Oxygen atoms (since 3 is the subscript for the nitrate group). Thus, we multiply 4 (formula units) by 3 (Oxygen atoms in each unit) and then multiply by 2 (since there are 2 nitrate groups in each formula unit), which gives us 24 Oxygen atoms.
So, the final count for 4Zn(NO₃)₂ is:
- Zn = 4
- N = 8
- O = 24
Process for Other Compounds:
Following the same logic, let’s break down some of the compounds:
- 4K₂CO₃ (Potassium Carbonate):
- K (Potassium): 4 formula units × 2 K atoms per formula unit = 8 K atoms.
- C (Carbon): 4 formula units × 1 C atom per formula unit = 4 C atoms.
- O (Oxygen): 4 formula units × 3 O atoms per formula unit = 12 O atoms.
- 3Na₂SO₄ (Sodium Sulfate):
- Na (Sodium): 3 formula units × 2 Na atoms per formula unit = 6 Na atoms.
- S (Sulfur): 3 formula units × 1 S atom per formula unit = 3 S atoms.
- O (Oxygen): 3 formula units × 4 O atoms per formula unit = 12 O atoms.
- 12NaBr (Sodium Bromide):
- Na (Sodium): 12 formula units × 1 Na atom per formula unit = 12 Na atoms.
- Br (Bromine): 12 formula units × 1 Br atom per formula unit = 12 Br atoms.
- 6Ba(MnO₄)₂ (Barium Permanganate):
- Ba (Barium): 6 formula units × 1 Ba atom per formula unit = 6 Ba atoms.
- Mn (Manganese): 6 formula units × 2 Mn atoms per formula unit = 12 Mn atoms.
- O (Oxygen): 6 formula units × 4 O atoms per formula unit × 2 = 48 O atoms.
General Method:
- Look at the chemical formula of the compound.
- Identify the number of atoms of each element within one formula unit (using subscripts).
- Multiply the number of atoms by the quantity of formula units or molecules.
- Write the total count for each element.
Explanation:
Counting atoms involves understanding the molecular formula of a compound, where the subscripts tell you how many atoms of each element are present in a single unit of the compound. By knowing how many formula units or molecules you have, you can calculate the total number of atoms by multiplying the subscript of each element by the number of formula units. This method works for all chemical compounds, whether ionic or covalent, as the basic principle of molecular structure holds true across all compound types.