Answer:
Advantages:
1. Grouping of elements. He generalized the study of the elements then known to a study of mere 8 groups.
2. Gaps for undiscovered elements. Mendeleev left some gaps in his periodic table. These gaps were left for subsequent inclusion of elements not known at that time. He correctly thought that such elements would be discovered later.
3. Prediction of properties of undiscovered elements. He predicted the properties of then unknown elements om the basis of properties of elements lying adjacent to the vacant slots.
4. Incorrect masses corrected. He was able to correct the values of atomic mass of elements like gold and platinum by placing these elements strictly on the bases of similarities in their properties.
Disadvantages:
1. Anomalous pairs: Argon with atomic mass 39.9 precedes potassium with atomic mass 39.1.
Cobalt with atomic mass 58.9 precedes nickel with atomic mass 58.6.
Tellurium with atomic mass 127.6 precedes iodine with atomic mass 126.9.
2. Position of isotopes: According to Mendeleev's periodic law, isotopes of an element must be given separate places in the periodic table since they have different atomic masses. But they were not assigned separate places.
3.Grouping of chemically dissimilar elements: Elements such as copper and silver bear no resemblance to alkali metals but they have placed in separate groups.
4.Separation of chemically similar elements: Elements that are chemically similar, such as gold and platinum have been placed in separate groups.
5.Electron arrangement: It does not explain the electron arrangement of elements.
6. Position of Hydrogen: It was not given in a fixed position.Explanation:
The Mendeleev periodic table has strengths in its predictive power, organization of elements, and observation of periodic trends. However, it has weaknesses in incomplete representation, limited understanding of atomic structure, and challenges in placing rare earth elements.
The Mendeleev periodic table, developed by Dmitri Mendeleev in the 19th century, laid the foundation for the modern periodic table. It has several strengths and weaknesses, which are outlined below:
Strengths of the Mendeleev periodic table:
Predictive Power: One of the major strengths of the Mendeleev periodic table is its ability to predict the existence and properties of yet-to-be-discovered elements. Mendeleev left gaps in the periodic table, accurately predicting the properties of elements that were later discovered and filled in those positions.
Periodic Trends: The Mendeleev periodic table organizes elements in a way that allows for the observation of periodic trends. Elements within the same group (vertical column) exhibit similar chemical properties and have similar valence electron configurations. This periodicity helps in understanding the behavior and reactivity of elements.
Classification of Elements: The Mendeleev periodic table classifies elements based on their atomic number and chemical properties. It provides a systematic arrangement of elements, allowing scientists to organize and study them more efficiently.
Weaknesses of the Mendeleev periodic table:
Incomplete Representation: The Mendeleev periodic table, when initially proposed, had gaps for undiscovered elements. While Mendeleev made accurate predictions, some of the gaps were filled in later with elements that did not necessarily match the properties initially predicted. This incomplete representation can be seen as a weakness.
Limited Understanding of Atomic Structure: At the time of Mendeleev's development of the periodic table, the understanding of atomic structure was incomplete. The periodic table was based on elemental properties without the knowledge of atomic numbers or the electron configuration of elements. This limitation hindered the ability to explain certain observed trends and properties accurately.
Lack of Internal Structure: The Mendeleev periodic table did not provide a detailed understanding of the internal structure of atoms or the arrangement of electrons in energy levels. It primarily focused on organizing elements based on their chemical properties and atomic weights, lacking the underlying atomic structure information.
Rare Earth Element Placement: Mendeleev faced challenges in placing the rare earth elements in the periodic table. Initially, he grouped them together as a separate series, but later refinements led to the placement of the rare earth elements within the main body of the table. The difficulty in organizing these elements reflects a weakness in the early understanding of their properties and arrangement.
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Which of the following is NOT a characteristic of a compound?
A. has different properties from the elements that formed it
B. pure substance made of two or more elements
C. can be represented by a chemical formula
D. different samples have different properties
Answer:
I think it's D
sorry if I'm wrong.
Explanation:
Options that are not characteristics of compound in the question is D. different samples have different properties.
A compound can be regarded as a substance which is formed by chemical combination of two or more elements.Examples of compound are water ( H2O), Sodium chloride ( NaCl)Some of the properties of a compound are;
A compound will always has a different properties which is different from the properties of each of the elements making up the compound.A compound are formed as a result of two or more elements that combined chemically.A compound can be identified with its chemical formula.Therefore, option D is correct because a compound will only has its own properties not that
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3. compounds in which elements are held together by covalent bonds...keeps their own properties
A polar molecule
B. element
C. compound
D. molecule
Which can change from one state of matter to another at the temperatures and pressures experienced at Earth’s surface?
oxygen
carbon dioxide
water
nitrogen
Describe how the particle motion is different from state to state.
Answer:
The particles in a gas are moving very quickly in random directions.
The particles in a solid are tightly packed and locked in place, and they are vibrating in their place.
The particles in a liquid are close together (touching) but they are able to move/slide/flow past each other.
brainliet please?
x
Please answer correctly !!!!!!!! Will mark brainliest !!!!!!!!!!!!!!
Answer: uuhhhh pass
Explanation:
Answer:
It should be 0.8mL.
Explanation: Because you would subtract what the rock would be without the water.
[tex]5.6-4.8=0.8[/tex] Simple C:
explain how to balance the chemical equation, KClO3 ⟶ KCl + O2 and include all steps
The balance of chemical equation : 2KClO₃ ⟶ 2KCl + 3O₂
Further explanationEqualization (balance) of chemical reactions can be done using variables. Steps in equalizing the reaction equation:
1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c, etc. 2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index (subscript) between reactant and product 3. Select the coefficient of the substance with the most complex chemical formula equal to 1Reaction
[tex]\tt KClO_3\Rightarrow KCl+O_2[/tex]
1. Coefficient
KClO₃ ⟶ aKCl + bO₂
2. Equation
K ⇒ left =1, right=a ⇒a=1
Cl⇒ left =1, right=a ⇒a=1
O ⇒ left = 3, right = 2b ⇒3=2b, b = 1.5
The equation turns into :
KClO₃ ⟶ KCl + 1.5O₂
multiplied by 2
2KClO₃ ⟶ 2KCl + 3O₂
What is the frequency of an event?
Group of answer choices
Probability
Degree
Expected occurrence
Identification
Answer:
Probability
Explanation:
Why were enslaved Africans in high demand in the southern colonies?
Answer:
Slaves were in high demand in the southern colonies because they were the main source of labor. ... Bacon and others colonists wanted to take the Natives land.
Explanation:
HOPE THIS HELPED ❤✨
I need help with these two questions
halogens have 7
allali have 2
noble gases have 8
K = 1
P = -3
Ra= 7
Cl = -1
N = 5
O = 6
psoriasis is a disease that causes a red rash on the skin. which body system does psoriasis affect?
a. respiratory
b. integumentary
c. immune
d. digestive
e. circulatory
Answer:
The answer to this question is integumentary.
Explanation:
The answer is that because that is your skin area and so if you have a rash then if will affect that part.
It's b. integumentary
I got the test right
K+ Cl2 → КСІ balance equation
What volume of silver metal will weigh exactly 2500g. The density of silver is 10,5 g/cubic centimeters.
Answer:
26250 cubic centimeters
Explanation:
Which symbol and unit of measurement are used for resistance?
symbol: R: unit :
symbol: 0; unit: R
symbol: R: unit o
symbol: R: unit R
Answer:
Unit of resistance is Ω (Omega).
Explanation:
The ability to measure the oppose the flow of electric current is called resistance of a circuit. Its relation with voltage and current is given by Ohm's law as follows :
V = IR
R is resistance
Its unit is Omega and it is represented by Ω.
The unit of the electrical resistance is ohm Ω
The symbol of resistance is R.
Hence Option A) Symbol: R, Unit : Ω is the correct answer
What is resistance?Resistance is simply the measure of the opposition to current flow in an electrical circuit.
Ohm’s law states that the potential difference between two points is directly proportional to the current flowing through the resistance.
V = I × R
Where;
V is the voltage or potential difference. I is the current.R is the resistance.The unit of the electrical resistance is ohm Ω
The symbol of resistance is R.
Hence Option A) Symbol: R, Unit : Ω is the correct answer
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Which statement offers an explanation for why some parts of John Dalton's atomic theory were proven to be false?
Scientists today are more diverse and have more educational training
Mistakes were made in key calculations during experimenting
Extensive repeated testing was not completed to verify the results
Technology available at that time was limited.
Answer:d
Explanation:
Answer:
The answer is D
Explanation:
I took the test!
The kinetic energy of a moving object depends on its mass and its
a. volume.
b. velocity.
c. distance.
d. acceleration.
how long will take an object traveling at 25 m/s to reach a distance of 125 meters?
Answer:
5s
Explanation:
Which cell organelle controls the activities for the cell?
Answer:
[tex]the \: nucleus \:[/tex]
Explanation:
[tex]the \: nucleus \: is \: organelle \: that \: controls \\ \:a ll \: cellular \: activities.[/tex]
What all indicates a CHEMICAL change? *
A Solid melting into a liquid
After the change the substance is still reactive with oxygen
One substance becomes two new substances
The melting point was 100 deg C but after the change the melting point was 256 deg
C.
one substance becomes two new substances
If a football is 625 mL volume and 0.64 g/mL density what is the mass
What element is the only Noble Gas in the s-block?
Answer:
Helium
Explanation:
Answer:
helium i guess i m not sure
The rows in the periodic table are called periods.
What is true about elements in the same period?
Answer:
elements in the same period have the same number of shells
the period number the element is in, that is the number of shells it has.
What happens if an organism cannot carry out its life function?
Answer:
organisms cannot stay with out getting nutrients as they will not be able to repair them selves or produce energy.
Explanation:
Hi I really need help
Answer:
A
Explanation:
a person who has non-functional cone type won't be able to identify the_____________of
fill in the blank.
A.color
B. shape
C. size
Answer:
A
Explanation:
more domunit
1 point
Nitrogen has three occurring isotopes: Nitrogen-13, Nitrogen-14, Nitrogen-15. Which isotope is the most abundant?
Explanation:
Nitrogen-14 is the most abundant isotopes of Nitrogen.
A star's mass determines the —
A) shape of a Star
B) location of a star
C) length of its lifecycle
D) galaxy it belongs to
the number of protons will tell you what elements it is. T or F plzz help
Answer:
True
Explanation:
There are two ways to tell elements apart from each other: the atomic number or the number of protons. The atomic number tells the number of protons in the element.
For example:
There are two given elements. One has 3 protons and an atomic number of 3 while the other has 7 protons and an atomic number of 7. Which one is Lithium?
Lithium has an atomic number of 3, which means it has three protons, which means Lithium is the one with 3 protons.
What mass of ethanol will All
a 250.0 ml container if its
density is 0.789 g/ml?
Answer:
The answer is 197.25 gExplanation:
The mass of a substance when given the density and volume can be found by using the formula
mass = Density × volumeFrom the question
volume = 250 mL
density = 0.789 g/ml
So we have
mass = 250 × 0.789
We have the final answer as
197.25 gHope this helps you
Find the percent of oxygen in CaClO3)2 Show your work
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Answer:
WOWKFBBAI9AIEHEBFKCOAKQQ