Answer:
A
Explanation:
more domunit
what are the strengths and weaknesses of the Mendeleev periodic table?
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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4. This group of substances tend to be malleable, ductile, and have relatively high melting points.
They are
(2 Points)
A.noble gases
B.nonmetals
C.metals
D.halogens
Answer:
The answer is metals
The inflation of airbags is due to the breakdown of a single chemical substance into two separate substances. Two molecules of sodium azide (NaN3) break down into sodium (Na) and nitrogen gas (N2) during the reaction. How many sodium (Na) atoms are produced in the reaction? 1 Na atom 2 Na atoms 3 Na atoms
Answer:
The correct answer is 2 Na atoms
Explanation:
To determine the number of sodium atoms produced in this reaction, the reaction described in the question must be written out in an equation and then balanced
2NaN₃ ⇒ 2Na + 3N₂
From the equation above, it can be deduced that the number of sodium atoms produced in the reaction described in the question is 2
Answer:
C) 2 Na atoms
Explanation:
Obi is trying to determine if a powdery, solid substance is an element or a compound. After recording some observations, he strongly heats a sample of the solid over a burner flame. After fifteen minutes, he turns off the flame and allows the sample to cool. He records his final observations in the data table.
Which is the best explanation of his results?
The heating changed some of the sample to gas, causing the mass to decrease without breaking down the sample. Therefore, the original sample is a compound.
The appearance stayed the same, showing that the sample was not broken down by heating. Therefore, the original substance is an element.
The mass decreased during heating and some of the impurities escaped. Therefore, the original substance is an element.
The chemical reaction with acid changed, showing that the sample was broken down by heating. Therefore, the original substance is a compound
Answer: I am thinking C maybe.
Explanation: I don't if this is right but I think it is C.
Answer:
D
Explanation:
Took the test on edge...
I think colloids are
heterogeneous
because ____________
___________________
the particles do not dissolve completely..
Explain in your own words what chemical change is
Answer:
A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust.
Explanation:
Answer: when one chemical substance is transformed into one or more different substances.
Explanation:
Which hypothesis is testable using a scientific experiment?
A. A fried egg is better than a hard-boiled egg.
B. Brown eggs are more attractive than white eggs.
C. Eggs with large yolks are more expensive than eggs with small
yolks.
D. You can boil an egg faster at high altitudes than at sea level.
12. A 100.00-gram sample of naturally occurring boron
contains 19.78 grams of boron-10 (atomic mass =
10.01 atomic mass units) and 80.22 grams of
boron-11 (atomic mass = 11.01 atomic mass units).
Which numerical setup can be used to determine the
atomic mass of naturally occurring boron?
A) (0.1978)(10.01) + (0.8022)(11.01)
B) (0.8022)(10.01) + (0.1978)(11.01)
C) (0.1978)(10.01)/(0.8022)(11.01)
D) (0.8022)(10.01)/(0.1978)(11.01)
It’s A) (0.1978)(10.01) + (0.8022)(11.01)
Relative and average atomic mass both describe properties of an element related to its different isotopes. Out of these two Relative atomic mas is more accurate. Therefore option A is correct option.
What is mass?Mass defines the quantity of a substance. It is measured in gram or kilogram. Average mass is the mass of atoms of an element that are isotopes. It can be calculated by multiplying mass of a isotope to natural abundance of that isotope.
Mathematically,
average atomic mass= ∑(relative abundance x mass of isotope)
average atomic mass boron= (relative abundance boron-10 x mass of isotope boron-10)+(relative abundance boron-11 x mass of isotope boron-11 )
average atomic mass boron=(0.1978)(10.01) + (0.8022)(11.01)
Therefore option A is correct option.
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7. The density of gasoline is 0.70 g/cm². How many cm of gasoline have a mass of 80
g?
A 875 cm3
B 88 cm3
C 1,143 cm3
D 114 cm3
Answer Is C 1,143
Explanation:
Which situation describes the best example of rotational motion?
Craig sent the pool ball spinning toward the side pocket.
The skater repeated the figure eight on the ice.
Sara spun the dreidel on its pointed end.
The mouse ran in circles around the mousetrap.
Answer:
The actual Answer is :
C. Sara spun the dreidel on its pointed end.
Explanation:
there you go bruh brainliest pls
Answer: It’s C
Explanation:
It’s showing rotational motion duhhh :3
Calculate the volume of a rock that has a mass of 24 g and a density of 8 g/mL
Answer:
24g÷8g/ml=3
volume =3
Bill Nye said the air pressure makes things what?
What does it mean for an element to be oxidized?
A. The element is a spectator ion in a chemical reaction.
B. The element has gained one or more electrons in a reaction.
C. The element has lost one or more electrons in a reaction.
D. The element has bonded to another element with opposite charge
Answer:
B
Explanation:
Oxidation occurs when an atom molecule or ion loses one or more electrons in a chemical reaction when oxidation occurs the oxidation state of the chemical species increases oxidation doesn't necessarily involve oxygen originally the term was used when oxygen caused electron loss in a reaction hope this helped. :)
An element is oxidized when It has loses one or more electrons in a chemical reaction. Therefore, Option (C) is correct.
What is Oxidation ?The loss of electrons, gain of oxygen or loss of hydrogen will be considered as Oxidation.
The gain of electrons, loss of oxygen or gain or hydrogen will be considered as the Reduction.
Rusting is one of the popular example of oxidation.
Therefore, An element is said to be oxidized when It has lost one or more electrons in a reaction.
Hence , Option (C) is correct.
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Chemical bond formation might take place due to the interaction between a(n) _______ and an anion
A.magnetic
B.valence
C.electrostatic
D.cation
1. An atom has 6 protons, 6 neutrons, and 6 electrons. What is the charge of the
atom's nucleus?
A.+6
B.+12
C.-6
D.-18
Answer:
+6
+6
+6
+6
+6
+6answer given
thanks
Electron Dot Structures
Draw the electron dot structures for the following elements:
Magnesium (Mg)
Lithium (Li)
Argon (Ar)
Carbon (C)
Sulfur (S)
Helium (He)
Aluminum (Al)
Nitrogen (N)
Silicon (Si)
Hydrogen (H)
Calcium (Ca)
Neon (Ne)
Potassium (K)
Boron (B)
Chlorine (Cl)
Answer:
surf (S)
tide (T)
champion (C)
Explanation:
wag mo nlng pansinin
6. What is one way a star with much more mass than the sun can end up?
white dwarf
red giant
neutron star
red dwarf
Answer:
neutron star
Explanation:
A massive star (More massive than the star) will undergo a supernova explosion. If the remnant of the explosion is 1.4 to about 3 times as massive as our Sun, it will become a neutron star. The core of a massive star that has more than roughly 3 times the mass of our Sun after the explosion will do something quite different
2. Mixtures can be solid, liquid or gas. It can be homogeneous or
heterogeneous and are made up of two or more components. Which of
the following mixtures where components are not visible??
Answer:
A solution is a special type of homogeneous mixture where the ratio of solute to solvent remains the same throughout the solution and the particles are not visible with the naked eye, even if homogenised with multiple sources.
Explanation:
Mixtures can be either homogeneous or heterogeneous': a mixture in which constituents are distributed uniformly is called homogeneous, such as salt in water, otherwise it is called heterogeneous, such as sand in water.
Describe the three phases of matter (solid, liquid, and gas) in terms of particle spacing, ability to fill shape and volume of container, energy of particles , and strength of intermolecular forces
Answer: solids are tense but spread out. Gas is spread out completely and liquid is all together
Explanation:
how many atoms does Mg(NO3)2 have thanks
Answer: Magnesium nitrate compound contains one atom for magnesium, two atoms for nitrogen, and six atoms for oxygen.
CREDIT safsaf
Explain what intermolecular forces are, and how they are easily overcome.
Explanation:
Intermolecular forces are forces that exist between two or more molecules and they can be overcome at high temperatures.
if the gas has a volume of 20 L at a temperature of 25 Celsius what is the volume of the gas when it is heated to 100°C if the pressure remains constant
Answer:
i have no idea
Explanation:
lol
Answer:
this has to do with gas law
Explanation:
Charles law
v1=20
T1=25
V2=?
T2=100
hence V1/T1=V2/T2
V2=V1*T2/T1
V2=20*25/100
V2=5
What do these two changes have in common?
using a large magnet to remove pieces of iron from a junkyard
rain forming in a cloud
Select all that apply.
Both are caused by heating.
Both are only physical changes.
Both conserve mass.
Both are chemical changes.
Answer: Both are only physical changes.
Explanation:
Both are only physical changes.
• The material, which takes part in the change is structurally similar after and before the change is known as the physical change.
• The cloud formation is a physical change as when evaporation of water takes place it goes into the air and produces cloud by the process of condensation. The same water goes back to earth by the process of precipitation and this get repeated again and again.
• A chemical change takes place when formation of new substance takes place by combining two substances. In the case, when a magnet picks up iron in a junkyard, one is still having an iron and a magnet, no formation of substance is taking place. So it is a physical change.
Thus, both the given processes are examples of only physical changes.
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Match each label below with the appropriate term. Note: there may be more than one correct answer.
nonbonding electrons
sigma bond
represents two electrons
Answer: sigma bond
Represents two electrons
Explanation:
E2020
Answer:
Sigma Bond AND Represents two electrons.
Explanation:
A scientist is studying the liquid shown here. She thinks the liquid is a mixture. Describe an investigation she could do to demonstrate that the liquid is in fact a combination of substances.
( please help it’s due today lol! i will mark your answer as brainliest or whatever .)
Answer: Measure the density
Explanation: pretty sure the density could identify if it is a mixture or a pure substance
Which substances from the simulation are more alkaline than water?
Which
Answer:
The substances more alkaline than water are;
1) Spit, 2) Blood, 3) Hand Soap, and 4) Drain Cleaner
Explanation:
The diagram in the simulation displays a list of liquid substances, arranged from bottom to top in the order of increasing alkalinity.
The ph of water is 7.0
The ph of spit (saliva) is between 6.2 and 7.6
The ph of blood is about 7.4
The ph of hand soap is between 9 and 10
The ph of drain cleaner is between 12 and 14.
How does the snake's skull allow it to eat large prey?
A. The jaw can crush the prey,
B. The teeth can grind the prey.
O C. The jaw can open wide around the prey.
D. The teeth can lock together around the prey,
What is an indicator? What does it tell you about solutions?
Answer:
Pure water is neutral, and so is petrol. An indicator is a substance that changes colour when it is added to acidic or alkaline solutions. You can prepare homemade indicators from red cabbage or beetroot juice - these will help you see if a solution is acidic or alkaline.
Why does oil float and not sink?
Answer:
because it has more density than water
Answer:
This is because oil is less dense than water and therefore it floats to the surface.
Is this a chemical reaction? Explain your reasoning. (Will give brainliest)
yes , this is a reaction.
in this sodium hydroxide reacts with copper sulfate