Elements, Compounds, and Mixtures Worksheet for 6th - 10th Grade ... - Free Printable
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Step-by-step solution for: Elements, Compounds, and Mixtures Worksheet for 6th - 10th Grade ...
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Step-by-step solution for: Elements, Compounds, and Mixtures Worksheet for 6th - 10th Grade ...
Let's solve the problems step by step:
---
#### Part (a): Approximately how many elements have been discovered? Circle the correct answer.
- Options: 10, 100, 1000
- Correct Answer: 100
Explanation:
The periodic table currently contains approximately 118 elements. Among these, about 94 are naturally occurring, and the rest are synthetic elements created in laboratories. Therefore, the closest option is 100.
---
#### Part (b): Which of the following is true about the atoms in an element?
- Options:
1. All of the atoms in an element are different.
2. All of the atoms in an element are the same.
3. In some elements the atoms are all the same but in others they are all different.
- Correct Answer: All of the atoms in an element are the same.
Explanation:
An element is defined as a substance consisting of only one type of atom. All atoms of a given element have the same number of protons in their nucleus, which determines the element's identity. While isotopes of an element may differ in the number of neutrons, they still belong to the same element. Therefore, the correct statement is that all atoms in an element are the same.
---
#### Part (c): The diagrams below show the atoms in three different substances. Which of the diagrams could show an element and which could not? In each case explain your answer in the space next to the diagram.
##### Diagram 1:
- Description: All the circles are identical.
- Answer: This diagram could show an element.
- Explanation: An element consists of only one type of atom. Since all the circles are identical, this represents a pure element.
##### Diagram 2:
- Description: There are two types of molecules shown: one with 2 atoms and one with 3 atoms.
- Answer: This diagram could not show an element.
- Explanation: An element consists of only one type of atom. Here, we see molecules with different compositions (e.g., diatomic and triatomic), indicating a compound or a mixture, not a pure element.
##### Diagram 3:
- Description: There are two types of atoms shown (circles of different sizes).
- Answer: This diagram could not show an element.
- Explanation: An element consists of only one type of atom. Here, we see two different types of atoms, indicating a compound or a mixture, not a pure element.
---
#### Part (d): Methane is a compound with the formula CH₄. Explain why we cannot find methane on the periodic table.
- Answer: Methane (CH₄) is a compound, not an element. The periodic table lists only elements, which are substances made up of only one type of atom. Methane is composed of both carbon (C) and hydrogen (H) atoms bonded together, so it is not an element and therefore cannot be found on the periodic table.
---
#### Part (e): A student wrote the symbol for cobalt as CO. Explain why this is incorrect and what this actually shows.
- Answer: The symbol for cobalt is simply "Co" (with a capital "C" and a lowercase "o"). Writing "CO" is incorrect because "CO" represents carbon monoxide, a compound consisting of one carbon atom and one oxygen atom. The periodic table uses unique one- or two-letter symbols for each element, and "CO" is not a valid symbol for any single element.
---
1. Part (a): Circle 100
2. Part (b): Choose All of the atoms in an element are the same
3. Part (c):
- Diagram 1: Could show an element (all atoms are the same)
- Diagram 2: Could not show an element (molecules with different compositions)
- Diagram 3: Could not show an element (two different types of atoms)
4. Part (d): Methane is a compound, not an element, so it cannot be found on the periodic table.
5. Part (e): "CO" is incorrect for cobalt; it represents carbon monoxide, a compound.
---
\[
\boxed{100, \text{"All of the atoms in an element are the same"}, \text{Diagram 1 could show an element; Diagrams 2 and 3 could not}, \text{Methane is a compound}, \text{"CO" represents carbon monoxide}}
\]
---
Problem 1: The periodic table shows us the elements.
#### Part (a): Approximately how many elements have been discovered? Circle the correct answer.
- Options: 10, 100, 1000
- Correct Answer: 100
Explanation:
The periodic table currently contains approximately 118 elements. Among these, about 94 are naturally occurring, and the rest are synthetic elements created in laboratories. Therefore, the closest option is 100.
---
#### Part (b): Which of the following is true about the atoms in an element?
- Options:
1. All of the atoms in an element are different.
2. All of the atoms in an element are the same.
3. In some elements the atoms are all the same but in others they are all different.
- Correct Answer: All of the atoms in an element are the same.
Explanation:
An element is defined as a substance consisting of only one type of atom. All atoms of a given element have the same number of protons in their nucleus, which determines the element's identity. While isotopes of an element may differ in the number of neutrons, they still belong to the same element. Therefore, the correct statement is that all atoms in an element are the same.
---
#### Part (c): The diagrams below show the atoms in three different substances. Which of the diagrams could show an element and which could not? In each case explain your answer in the space next to the diagram.
##### Diagram 1:
- Description: All the circles are identical.
- Answer: This diagram could show an element.
- Explanation: An element consists of only one type of atom. Since all the circles are identical, this represents a pure element.
##### Diagram 2:
- Description: There are two types of molecules shown: one with 2 atoms and one with 3 atoms.
- Answer: This diagram could not show an element.
- Explanation: An element consists of only one type of atom. Here, we see molecules with different compositions (e.g., diatomic and triatomic), indicating a compound or a mixture, not a pure element.
##### Diagram 3:
- Description: There are two types of atoms shown (circles of different sizes).
- Answer: This diagram could not show an element.
- Explanation: An element consists of only one type of atom. Here, we see two different types of atoms, indicating a compound or a mixture, not a pure element.
---
#### Part (d): Methane is a compound with the formula CH₄. Explain why we cannot find methane on the periodic table.
- Answer: Methane (CH₄) is a compound, not an element. The periodic table lists only elements, which are substances made up of only one type of atom. Methane is composed of both carbon (C) and hydrogen (H) atoms bonded together, so it is not an element and therefore cannot be found on the periodic table.
---
#### Part (e): A student wrote the symbol for cobalt as CO. Explain why this is incorrect and what this actually shows.
- Answer: The symbol for cobalt is simply "Co" (with a capital "C" and a lowercase "o"). Writing "CO" is incorrect because "CO" represents carbon monoxide, a compound consisting of one carbon atom and one oxygen atom. The periodic table uses unique one- or two-letter symbols for each element, and "CO" is not a valid symbol for any single element.
---
Final Answers:
1. Part (a): Circle 100
2. Part (b): Choose All of the atoms in an element are the same
3. Part (c):
- Diagram 1: Could show an element (all atoms are the same)
- Diagram 2: Could not show an element (molecules with different compositions)
- Diagram 3: Could not show an element (two different types of atoms)
4. Part (d): Methane is a compound, not an element, so it cannot be found on the periodic table.
5. Part (e): "CO" is incorrect for cobalt; it represents carbon monoxide, a compound.
---
Boxed Final Answer:
\[
\boxed{100, \text{"All of the atoms in an element are the same"}, \text{Diagram 1 could show an element; Diagrams 2 and 3 could not}, \text{Methane is a compound}, \text{"CO" represents carbon monoxide}}
\]
Parent Tip: Review the logic above to help your child master the concept of elements compounds worksheet.
