Educational worksheet on the periodic table with questions about elements, their properties, and historical context.

Let's solve this step by step.

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Part A: Fill in the blanks

We are given a list of words to choose from:

> repeating pattern, 50, periods, similar, center, 100, increasing, groups, properties, repeating patterns, far right, far left, protons

Now let’s go through each sentence and fill in the correct word(s).

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1. In 1869, Mendeleev published his arrangement of the known elements in the “periodic table”. Just over ____ elements were arranged using details of their ____ and compounds. This table revealed _________ in the chemical properties of the elements in the same vertical column.

- "Just over ____ elements" → Mendeleev had about 50 known elements at that time.
- "details of their ____ and compounds" → He used properties.
- "revealed _________ in the chemical properties..." → He noticed a repeating pattern (or repeating patterns) — both are possible, but repeating pattern is more commonly used in this context.

✔ So:
- Just over 50 elements
- details of their properties
- revealed repeating pattern

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2. The elements of the periodic table are arranged in the order of ________ atomic number. The atomic number reflects the number of ________ in the nucleus of each atom.

- Order of increasing atomic number.
- Atomic number = number of protons.

✔ So:
- increasing
- protons

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3. Elements are arranged in rows of increasing atomic numbers called ________. Elements with similar properties are arranged in the same vertical column, called ________.

- Rows = periods
- Vertical columns = groups

✔ So:
- periods
- groups

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4. Metals are grouped on the left and ________ of the periodic table. Gasses are positioned on the ________ of the periodic table (except hydrogen). Semiconductors are grouped between metals and non-metals and have some properties that are ________ to both types of elements.

- Metals are on the left and center (middle) of the table.
- Gases are on the far right (noble gases).
- Semiconductors have properties similar to both metals and non-metals.

✔ So:
- center
- far right
- similar

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✔ Final Answer for Part A:

> In 1869, Mendeleev published his arrangement of the known elements in the “periodic table”. Just over 50 elements were arranged using details of their properties and compounds. This table revealed repeating pattern in the chemical properties of the elements in the same vertical column.

> The elements of the periodic table are arranged in the order of increasing atomic number. The atomic number reflects the number of protons in the nucleus of each atom.

> Elements are arranged in rows of increasing atomic numbers called periods. Elements with similar properties are arranged in the same vertical column, called groups.

> Metals are grouped on the left and center of the periodic table. Gasses are positioned on the far right of the periodic table (except hydrogen). Semiconductors are grouped between metals and non-metals and have some properties that are similar to both types of elements.

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Part B: Answer the following questions

#### ① Which 3 elements are magnetic?

The three naturally magnetic elements are:
- Iron (Fe)
- Cobalt (Co)
- Nickel (Ni)

These are the only three elements that are ferromagnetic at room temperature.

✔ Answer: Iron, Cobalt, Nickel

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#### ② Which 2 elements are liquid at room temperature?

At room temperature (around 20–25°C):
- Mercury (Hg) – a metal, liquid
- Bromine (Br) – a non-metal, liquid

✔ Answer: Mercury and Bromine

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#### ③ Which element is used in batteries?

Many batteries use different elements, but one common example is:
- Lithium (Li) – widely used in lithium-ion batteries
- Others include Lead (Pb) in car batteries, Zinc (Zn) in alkaline batteries

But since it asks for one, the most significant modern answer is Lithium.

✔ Answer: Lithium

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#### ④ Which is a significant element found in eggs?

Eggs are rich in Sulfur (especially in proteins like cysteine and methionine), but also contain Phosphorus, Calcium, and Proteins.

However, a key element often highlighted is Sulfur due to its presence in egg whites and the smell of rotten eggs (hydrogen sulfide).

Alternatively, Calcium is important in eggshells (calcium carbonate).

But if we consider biological significance, Sulfur is essential in amino acids.

Still, a very common answer is Calcium, because of the eggshell.

But another strong candidate is Phosphorus, as it's part of DNA and cell membranes.

Wait — perhaps the best answer is Sulfur? Let’s think.

Actually, Nitrogen is also abundant in proteins.

But the most significant element in terms of nutritional value and commonly associated with eggs is Protein, which contains Carbon, Hydrogen, Oxygen, Nitrogen, and Sulfur.

But the question asks for an element.

A better-known fact: Eggs are high in protein, and sulfur-containing amino acids are present.

But the most prominent element in eggs? Probably Carbon, Oxygen, or Hydrogen — but not specific.

Wait — there’s a well-known fact: Sulfur gives off the smell when eggs rot.

But maybe the intended answer is Calcium because of the shell.

Alternatively, Phosphorus is important in energy storage.

But actually, the most significant element found in eggs could be Calcium due to eggshells.

But let’s look for a standard answer.

Another idea: Iodine? No.

Actually, Selenium is found in eggs, but not significant.

Perhaps the expected answer is Calcium, because eggshells are made of calcium carbonate.

✔ Answer: Calcium

Or possibly Sulfur, but Calcium is more likely expected.

Wait — check online sources: Eggs contain calcium, phosphorus, iron, sulfur, etc.

But the most significant might be Calcium due to the shell.

Alternatively, Protein is made of Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur — so Nitrogen is important.

But the most commonly referenced element in eggs is Calcium.

✔ Answer: Calcium

(Though Sulfur is also plausible.)

But based on typical curricula, Calcium is often mentioned.

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✔ Final Answers for Part B:

1. Iron, Cobalt, Nickel
2. Mercury and Bromine
3. Lithium (or Zinc, Lead — but Lithium is common)
4. Calcium (due to eggshells)

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✔ Full Completed Worksheet:

#### A. Fill in the blanks:

In 1869, Mendeleev published his arrangement of the known elements in the “periodic table”. Just over 50 elements were arranged using details of their properties and compounds. This table revealed repeating pattern in the chemical properties of the elements in the same vertical column.

The elements of the periodic table are arranged in the order of increasing atomic number. The atomic number reflects the number of protons in the nucleus of each atom.

Elements are arranged in rows of increasing atomic numbers called periods. Elements with similar properties are arranged in the same vertical column, called groups.

Metals are grouped on the left and center of the periodic table. Gasses are positioned on the far right of the periodic table (except hydrogen). Semiconductors are grouped between metals and non-metals and have some properties that are similar to both types of elements.

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#### B. Answer the following questions:

1. Iron, Cobalt, Nickel
2. Mercury and Bromine
3. Lithium
4. Calcium

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✔ These answers are accurate and align with standard chemistry knowledge.