links.
www.scilinks.org
topic: origin of
elements
code: hk81082

section 1 review

key ideas
1. describe how mendeleev organized his periodic table.
2. explain why mendeleev left a space for the unknown (at the time) element germanium in his periodic table.
3. state the property used to organize elements in the modern periodic table.
4. identify the following on the periodic table.
a. the chemical symbol for mercury
b. the period and group of gold
c. the atomic mass of iron
d. the atomic number of neon
e. the element represented by cu

Question

links.
www.scilinks.org
topic: origin of
elements
code: hk81082

section 1 review

key ideas
1. describe how mendeleev organized his periodic table.
2. explain why mendeleev left a space for the unknown (at the time) element germanium in his periodic table.
3. state the property used to organize elements in the modern periodic table.
4. identify the following on the periodic table.
   a. the chemical symbol for mercury
   b. the period and group of gold
   c. the atomic mass of iron
   d. the atomic number of neon
   e. the element represented by cu

Accepted Answer

### 1. Answer for "Describe how Mendeleev organized his periodic table."
# Brief Explanations:
Mendeleev organized his periodic table by arranging elements in order of increasing atomic mass. He grouped elements with similar chemical properties in the same vertical columns (groups). He also left spaces for undiscovered elements, predicting their properties based on the trends in the table.
# Answer:
Mendeleev organized his periodic table by arranging elements in order of increasing atomic mass and grouping elements with similar chemical properties in vertical columns (groups). He left spaces for undiscovered elements, predicting their properties.

### 2. Answer for "Explain why Mendeleev left a space for the unknown (at the time) element germanium in his periodic table."
# Brief Explanations:
Mendeleev noticed patterns in the properties of known elements. When arranging elements by atomic mass, he saw that the properties of elements repeated periodically. For germanium (then unknown), the position in the table (based on atomic mass and property trends) had no known element with matching properties. So he left a space, predicting a new element (germanium) would fill it, with properties matching the trend of the group and period.
# Answer:
Mendeleev left a space for germanium because, when arranging elements by atomic mass and grouping by similar properties, the position in the table (based on periodic property trends) had no known element with matching properties. He predicted a new element (germanium) would occupy this space, with properties consistent with the group/period trends.

### 3. Answer for "State the property used to organize elements in the modern periodic table."
# Brief Explanations:
In the modern periodic table, elements are organized by increasing atomic number (the number of protons in an atom's nucleus). This is because atomic number is a fundamental property that determines an element's chemical behavior, and when elements are arranged by atomic number, their properties repeat periodically in a more consistent way than when arranged by atomic mass.
# Answer:
The property used to organize elements in the modern periodic table is atomic number (the number of protons in an atom's nucleus).

### 4. Answers for the sub - questions:
#### a. the chemical symbol for mercury
# Brief Explanations:
By referring to the periodic table, we know that the chemical symbol for mercury is Hg. This is a standard notation for the element mercury, derived from its Latin name "hydrargyrum".
# Answer:
The chemical symbol for mercury is Hg.

#### b. the period and group of gold
# Brief Explanations:
Gold (Au) is located in period 6 (the 6th horizontal row) and group 11 (the 11th vertical column, also known as the coinage metals group) of the periodic table. We determine this by looking at the horizontal (period) and vertical (group) position of gold on the periodic table.
# Answer:
Gold (Au) is in period 6 and group 11.

#### c. the atomic mass of iron
# Brief Explanations:
Looking at the periodic table, the atomic mass of iron (Fe) is approximately 55.845 atomic mass units (amu). This value is based on the average mass of the isotopes of iron, taking into account their relative abundances.
# Answer:
The atomic mass of iron (Fe) is approximately 55.845 amu.

#### d. the atomic number of neon
# Brief Explanations:
The atomic number of an element is equal to the number of protons in its nucleus. For neon (Ne), by referring to the periodic table, we find that its atomic number is 10.
# Answer:
The atomic number of neon (Ne) is 10.

#### e. the element represented by Cu
# Brief Explanations:
By referring to the periodic table, the chemical symbol Cu represents the element copper. The symbol Cu is derived from the Latin name "cuprum" for copper.
# Answer:
The element represented by Cu is copper.

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1. Answer for "Describe how Mendeleev organized his periodic table."

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2. Answer for "Explain why Mendeleev left a space for the unknown (at the time) element germanium in his periodic table."