Sci 1 Ch 2 Flashcards
1
Q
Who developed the Law of Octaves?
A
John Newlands
Newlands was an English scientist who arranged elements based on atomic masses.
2
Q
In what year did Newlands arrange the elements according to their atomic masses?
A
1866
This was when Newlands first proposed his Law of Octaves.
3
Q
What is the main idea of Newlands’ Law of Octaves?
A
Every eighth element has similar properties to the first one
For example, sodium (Na) is similar to lithium (Li).
4
Q
Which element is the lightest in Newlands’ arrangement?
A
Hydrogen
Hydrogen is the first element in the periodic table.
5
Q
What musical analogy did Newlands use to describe the periodicity of elements?
A
He compared it to octaves in music
Similarities in elements were likened to musical notes.
6
Q
How many main notes are in the Indian music system?
A
Seven
The notes are Sa, Re, Ga, Ma, Pa, Dha, Ni.
7
Q
What is the term used for the collection of seven main notes in Indian music?
A
‘Saptak’
‘Saptak’ represents a complete musical scale in Indian music.
8
Q
What limitation was found in Newlands’ octaves?
A
Applicable only up to calcium
Newlands’ law could not accommodate elements discovered later.
9
Q
What was the arrangement format used by Newlands for the elements?
A
7 X 8 table
Newlands created a table with 56 boxes to fit known elements.
10
Q
Which two elements did Newlands place under the note ‘Do’?
A
Co and Ni
These metals were placed along with halogens under the same note.
11
Q
Who developed the periodic table of elements?
A
Dmitri Mendeleev
Mendeleev was a Russian scientist who created the table between 1869 and 1872.
12
Q
How many elements did Mendeleev arrange in his periodic table?
A
63 elements
Mendeleev arranged the elements based on their atomic masses.
13
Q
What fundamental property did Mendeleev use to arrange the elements?
A
Atomic mass
Mendeleev considered atomic mass as the standard for his arrangement.
14
Q
What did Mendeleev’s periodic table consider besides atomic mass?
A
Physical and chemical properties
The table was organized based on both properties and atomic mass.
15
Q
Who developed the Law of Octaves?
A
John Newlands
Newlands was an English scientist who arranged elements based on atomic masses.
16
Q
In what year did Newlands arrange the elements according to their atomic masses?
A
1866
This was when Newlands first proposed his Law of Octaves.
17
Q
What is the main idea of Newlands’ Law of Octaves?
A
Every eighth element has similar properties to the first one
For example, sodium (Na) is similar to lithium (Li).
18
Q
Which element is the lightest in Newlands’ arrangement?
A
Hydrogen
Hydrogen is the first element in the periodic table.
19
Q
What musical analogy did Newlands use to describe the periodicity of elements?
A
He compared it to octaves in music
Similarities in elements were likened to musical notes.
20
Q
How many main notes are in the Indian music system?
A
Seven
The notes are Sa, Re, Ga, Ma, Pa, Dha, Ni.
21
Q
What is the term used for the collection of seven main notes in Indian music?
A
‘Saptak’
‘Saptak’ represents a complete musical scale in Indian music.
22
Q
What limitation was found in Newlands’ octaves?
A
Applicable only up to calcium
Newlands’ law could not accommodate elements discovered later.
23
Q
What was the arrangement format used by Newlands for the elements?
A
7 X 8 table
Newlands created a table with 56 boxes to fit known elements.
24
Q
Which two elements did Newlands place under the note ‘Do’?
A
Co and Ni
These metals were placed along with halogens under the same note.
25
Who developed the periodic table of elements?
Dmitri Mendeleev
## Footnote
Mendeleev was a Russian scientist who created the table between 1869 and 1872.
26
How many elements did Mendeleev arrange in his periodic table?
63 elements
## Footnote
Mendeleev arranged the elements based on their atomic masses.
27
What fundamental property did Mendeleev use to arrange the elements?
Atomic mass
## Footnote
Mendeleev considered atomic mass as the standard for his arrangement.
28
What did Mendeleev's periodic table consider besides atomic mass?
Physical and chemical properties
## Footnote
The table was organized based on both properties and atomic mass.
29
What is the main idea behind Dobereiner's Triads?
Properties of elements are related to their atomic masses
## Footnote
Dobereiner grouped elements into triads based on similar chemical properties.
30
What is a triad in the context of Dobereiner's classification?
A group of three elements with similar chemical properties arranged by increasing atomic mass
## Footnote
The middle element's atomic mass is approximately the mean of the other two.
31
List the elements in Dobereiner's first triad.
* Lithium (Li)
* Sodium (Na)
* Potassium (K)
32
What is the second triad in Dobereiner's classification?
* Calcium (Ca)
* Strontium (Sr)
* Barium (Ba)
33
What is the smallest particle of matter called?
Atom
34
What are the three main types of elements?
* Metals
* Nonmetals
* Metalloids
35
What was Newlands' Law of Octaves?
A classification method where elements were arranged in groups of eight based on similar properties
## Footnote
This law suggests that every eighth element shares similar chemical properties.
36
What is the significance of the Modern Periodic Table?
It organizes elements based on increasing atomic number and groups them according to similar properties
## Footnote
The Modern Periodic Table reflects updated understanding of atomic structure.
37
True or False: All known elements can be classified into Dobereiner's Triads.
False
38
What is the average atomic mass of the middle element in a triad?
Approximately equal to the mean of the atomic masses of the other two elements
39
Fill in the blank: _______ suggested that properties of elements are related to their atomic masses.
Dobereiner
40
What did scientists aim to achieve by classifying elements?
To ease the study of a large number of elements by identifying patterns
## Footnote
This classification helps in understanding their properties and relationships.
41
What year did Dobereiner propose his classification system?
1817
42
The modern periodic table is divided into ______ block
Ans - 4blocks - S,P,D,F
43
Give an example of dorbereiner's traid
Li, Na, K(atomic mass)
Li-6. 9
Na-23. 0
K-39. 1
44
What are horizontal rows in the periodic table called?
Periods
## Footnote
In the periodic table, periods indicate the number of electron shells in the elements.
45
What are the vertical columns in Mendeleev's periodic table called?
Groups
## Footnote
Groups consist of elements that exhibit similar chemical properties.
46
According to Mendeleev, properties of elements are periodic functions of their _______.
Atomic masses
## Footnote
Mendeleev's periodic law states that properties repeat after a definite interval based on atomic mass.
47
What did Mendeleev state about the properties of elements?
Properties repeat after a definite interval
## Footnote
This was a key finding that led to the development of the periodic table.
48
Mendeleev found that elements with similar physical and chemical properties are grouped together based on their _______.
Molecular formulae of hydrides and oxides
## Footnote
This organization helped in predicting the properties of undiscovered elements.
49
Which properties did Mendeleev consider while organizing the periodic table?
* Chemical properties
* Physical properties
* Melting points
* Boiling points
* Densities
## Footnote
These properties were essential in grouping the elements.
50
True or False: Mendeleev's periodic table was based solely on atomic numbers.
False
## Footnote
Mendeleev's table was primarily organized by atomic mass.
51
While going from left to right in the periodic table, what trend is observed in the properties of elements?
Periodic changes in properties
## Footnote
This trend reflects the increase in atomic number and the corresponding changes in electron configuration.
52
Who was Dmitri Mendeleev?
A professor at St. Petersburg University and inventor of the periodic table of elements
## Footnote
Mendeleev's work laid the foundation for modern chemistry.
53
What years did Dmitri Mendeleev live?
1834-1907
## Footnote
Mendeleev's contributions to chemistry occurred during the 19th century.
54
What method did Mendeleev use to organize elements?
He made separate cards for every known element showing its atomic mass and arranged them according to atomic masses and properties
## Footnote
This method led to the creation of the periodic table.
55
What is the significance of the periodic table?
It organizes elements based on atomic mass and properties, allowing for the prediction of element behaviors
## Footnote
The periodic table is a fundamental tool in chemistry.
56
What were the general molecular formulae shown in Mendeleev's periodic table?
R'0, RO, etc.
## Footnote
These notations represent different types of compounds.
57
In the present system, how are the general molecular formulae represented?
R0, RO, etc.
## Footnote
This reflects advancements in chemical notation since Mendeleev's time.
58
What are noble gases?
Helium, neon, argon
## Footnote
Noble gases are a group of elements that were not initially included in Mendeleev's periodic table.
59
Where were noble gases placed in Mendeleev's periodic table?
In the zero group
## Footnote
This placement did not disturb the existing arrangement of elements.
60
What are the isotopes of chlorine?
Cl-35 and Cl-37
## Footnote
These isotopes have atomic masses of 35 and 37 respectively.
61
What is an amphoteric oxide?
An oxide that can act as both an acid and a base
## Footnote
Examples include gallium oxide (Ga2O3).
62
What is the formula of gallium oxide?
Ga2O3
63
What is the atomic mass of gallium?
68
64
What is the melting point of gallium in °C?
29.76
65
What is the density of gallium in g/cm³?
5.9
66
What are the predicted atomic masses for eka-boron, eka-aluminum, and eka-silicon?
44, 68, 72
## Footnote
These were the predicted atomic masses for elements that were later discovered.
67
What did Mendeleev keep vacant places in his periodic table for?
Undiscovered elements
68
What was revised to give beryllium its proper place in the periodic table?
The atomic mass of beryllium
69
What is the correct atomic mass of beryllium?
9.4
70
What principle did Mendeleev apply while arranging elements?
The properties of elements are a periodic function of their atomic masses
71
What does the success of Mendeleev's periodic table demonstrate?
The information available till then was not final and could change
72
True or False: Mendeleev's periodic table included all known elements at the time.
False
73
What were the names given to the three unknown elements predicted by Mendeleev?
Eka-boron, eka-aluminum, eka-silicon
74
What characteristic of science is highlighted by Mendeleev's periodic table?
Science is progressive and can revise old inferences
75
What was the importance of Mendeleev's method of classification of elements?
It predicted the properties of undiscovered elements
76
Names of eka - boron
Eka - aluminum
Eka - slilicon
Scandium(Sc)
Gallium(Ga)
Germanium ( Ge)
77
ls 2 periodic classification of elements science 1 10th std MH board
make a test paper of 80 marks with all the important question and trickiest questions also with mcq and true and false
## Periodic Classification of Elements – Science 1 (Class 10, MH Board)
### 80 Marks Test Paper
---
### **Section A: Multiple Choice Questions (MCQ) (1 × 10 = 10 marks)**
1. The number of electrons in the outermost shell of alkali metals is
(a) 1 (b) 2 (c) 3 (d) 7[5]
2. Who gave the Law of Octaves?
(a) Dobereiner (b) Newlands (c) Mendeleev (d) Moseley[1][5]
3. Which block contains all non-metals in the modern periodic table?
(a) s-block (b) p-block (c) d-block (d) f-block[5][8]
4. Atomic radius ________ down a group.
(a) increases (b) decreases (c) remains same (d) none[5]
5. The most electronegative element is
(a) Oxygen (b) Fluorine (c) Chlorine (d) Nitrogen[4]
6. The modern periodic law is based on
(a) Atomic mass (b) Atomic number (c) Valency (d) Density[1][4]
7. Which group contains noble gases?
(a) 1 (b) 2 (c) 17 (d) 18[5]
8. Which of the following is a metalloid?
(a) Na (b) Si (c) Mg (d) K[8]
9. The period number of an element is equal to
(a) Number of protons (b) Number of shells (c) Atomic number (d) Valency[4]
10. Which statement is true about elements in the same group?
(a) Same atomic number (b) Same valency (c) Same period (d) Same mass[4][5]
---
### **Section B: True or False (1 × 10 = 10 marks)**
1. Atomic radius decreases across a period from left to right.[5]
2. All elements in a period have the same number of valence electrons.
3. Mendeleev arranged elements according to increasing atomic mass.[1][4]
4. Noble gases are placed in Group 18 of the modern periodic table.[5]
5. Newlands’ Law of Octaves could be applied to all known elements.
6. Elements in the same group show similar chemical properties.[4][5]
7. The modern periodic table is also called the long form of the periodic table.[4]
8. Hydrogen is placed in Group 1 due to its electronic configuration.
9. The third period contains 18 elements.
10. Metalloids show properties of both metals and non-metals.
---
### **Section C: Short Answer Questions (3 × 10 = 30 marks)**
1. Define Dobereiner’s Triads with an example.[1][4]
2. State Mendeleev’s Periodic Law. Write any two limitations of Mendeleev’s periodic table.[1][4][6]
3. What is meant by periodicity in properties of elements? Give two examples.[1][4]
4. Write the electronic configuration of the following: 3Li, 14Si, 2He, 11Na, 15P. Which of these belong to period 3? Explain.[4]
5. Why are noble gases placed in a separate group?[6]
6. Compare the properties of metals, non-metals, and metalloids with examples.[1][4]
7. What is the significance of the modern periodic table? Mention any two advantages over Mendeleev’s table.[4][6]
8. Explain the trends in valency and atomic size in a group and a period.[4][5]
9. Give reasons:
a) Sodium is more reactive than magnesium.
b) Chlorine is a non-metal, but sodium is a metal.
10. Name:
a) The family of metals with valency one.
b) The family of non-metals with valency one.
c) Two metalloids present in period 2 and 3.[5]
---
### **Section D: Long Answer/Tricky Questions (5 × 6 = 30 marks)**
1. Describe the construction and features of the modern periodic table. How does it solve the anomalies of Mendeleev’s table?[1][4][6]
2. An element X has atomic number 17.
a) Write its electronic configuration.
b) Identify its group and period.
c) Predict its nature (metal/non-metal) and valency.
d) Write the formula of its hydride and oxide.[4][6]
3. State and explain Newlands’ Law of Octaves. Why did it fail for elements beyond calcium?[1][4][6]
4. Differentiate between groups and periods. Give one example each.[6]
give the answers
Certainly! Here are the **answers** to the test paper on **Periodic Classification of Elements** for Class 10 (MH Board):
---
## **Answers**
### Section A: Multiple Choice Questions (MCQ)
1. (a) 1
2. (b) Newlands
3. (b) p-block
4. (a) increases
5. (b) Fluorine
6. (b) Atomic number
7. (d) 18
8. (b) Si
9. (b) Number of shells
10. (b) Same valency
---
### Section B: True or False
1. True
2. False (Elements in the same period have different valence electrons)
3. True
4. True
5. False (It failed for elements beyond calcium)
6. True
7. True
8. True
9. False (Third period contains 8 elements)
10. True
---
### Section C: Short Answer Questions
1. **Dobereiner’s Triads:** Groups of three elements with similar chemical properties where the atomic mass of the middle element is approximately the average of the other two.
*Example:* Lithium (7), Sodium (23), Potassium (39).
2. **Mendeleev’s Periodic Law:** "The properties of elements are a periodic function of their atomic masses."
**Limitations:**
- Could not explain the position of isotopes.
- Some elements were placed out of order based on chemical properties.
3. **Periodicity:** Repetition of similar properties after regular intervals when elements are arranged in order of increasing atomic number.
*Examples:* Atomic size decreases across a period; valency changes periodically.
4. Electronic configurations:
- 3Li: 2,1
- 14Si: 2,8,4
- 2He: 2
- 11Na: 2,8,1
- 15P: 2,8,5
Elements in period 3: Na, Si, P (because they have 3 shells).
5. Noble gases are placed in a separate group (Group 18) because they are inert (chemically non-reactive) due to their complete valence shell.
6.
- Metals: Lustrous, malleable, good conductors (e.g., Na, Mg).
- Non-metals: Dull, brittle, poor conductors (e.g., Cl, S).
- Metalloids: Properties intermediate between metals and non-metals (e.g., Si, B).
7. **Significance of Modern Periodic Table:**
- Elements arranged by atomic number, solving anomalies of Mendeleev’s table.
- Groups and periods clearly define element properties.
**Advantages:**
- Position of isotopes explained.
- Predicts properties more accurately.
8.
- Valency in a group remains the same; in a period, it increases then decreases.
- Atomic size increases down a group; decreases across a period.
9.
a) Sodium is more reactive than magnesium because it has only one electron in its outer shell which is easily lost.
b) Chlorine is a non-metal because it gains electrons; sodium is a metal because it loses electrons.
10.
a) Alkali metals (Group 1)
b) Halogens (Group 17)
c) Boron (B) in period 2, Silicon (Si) in period 3
---
### Section D: Long Answer / Tricky Questions
1. **Modern Periodic Table:**
- Elements arranged in order of increasing atomic number.
- Groups: Vertical columns with elements having similar properties and same valency.
- Periods: Horizontal rows with increasing atomic number and changing properties.
**Features:**
- 18 groups and 7 periods.
- Transition metals in d-block.
- Lanthanoids and actinoids in f-block.
**Solves anomalies:**
- Corrects order where atomic mass was inconsistent.
- Places isotopes together.
2. Element X (Atomic number 17):
a) Electronic configuration: 2,8,7
b) Group 17 (Halogens), Period 3
c) Non-metal, valency 1 (needs 1 electron to complete octet)
d) Hydride: HCl (Hydrogen chloride), Oxide: Cl₂O₇ (Chlorine heptoxide)
3. **Newlands’ Law of Octaves:** Properties of elements repeat every eighth element when arranged by increasing atomic mass.
**Failure:** Did not work beyond calcium because new elements did not fit the pattern and transition metals disturbed the order.
4.
- **Groups:** Vertical columns with elements having similar properties and same valency.
- **Periods:** Horizontal rows where properties change gradually.
*Example Group:* Group 1 (Li, Na, K)
*Example Period:* Period 2 (Li, Be, B, C, N, O, F, Ne)
5.
a) Order of increasing atomic number: Na(11), Mg(12), Al(13), Si(14), P(15), S(16), Cl(17), Ar(18)
b) Classification:
- Metals: Na, Mg, Al
- Metalloids: Si
- Non-metals: P, S, Cl, Ar
