Answer:
•Atomic theory, ancient philosophical speculation that all things can be accounted for by innumerable combinations of hard, small, indivisible particles (called atoms) of various sizes but of the same basic material; or the modern scientific theory of matter according to which the chemical elements that combine to form the great variety of substances consist themselves of aggregations of similar subunits (atoms) possessing nuclear and electron substructure characteristic of each element. The ancient atomic theory was proposed in the 5th century BC by the Greek philosophers Leucippus and Democritus and was revived in the 1st century BC by the Roman philosopher and poet Lucretius. The modern atomic theory, which has undergone continuous refinement, began to flourish at the beginning of the 19th century with the work of the English chemist John Dalton. The experiments of the British physicist Ernest Rutherford in the early 20th century on the scattering of alpha particles from a thin gold foil established the Rutherford atomic model of an atom as consisting of a central, positively charged nucleus containing nearly all the mass and surrounded by a cloud of negatively charged planetlike electrons.
•With the advent of quantum mechanics and the Schrödinger equation in the 1920s, atomic theory became a precise mathematical science. Austrian physicist Erwin Schrödinger devised a partial differential equation for the quantum dynamics of atomic electrons, including the electrostatic repulsion of all the negatively charged electrons from each other and their attraction to the positively charged nucleus. The equation can be solved exactly for an atom containing only a single electron (hydrogen), and very close approximations can be found for atoms containing two or three electrons (helium and lithium). To the extent that the Schrödinger equation can be solved for more-complex cases, atomic theory is capable of predicting from first principles the properties of all atoms and their interactions. The recent availability of high-speed supercomputers to solve the Schrödinger equation has made possible accurate calculations of properties for atoms and molecules with ever larger numbers of electrons. Precise agreement with experiment is obtained if small corrections due to the effects of the theory of special relativity and quantum electrodynamics are also included.
I hope it's help you
Define terms element compound
Answer:
Elements are the simplest complete chemical substances.
Each element corresponds to a single entry on the periodic table.
An element is a material that consists of a single type of atom.
A compound consists of two or more types of elements held together by covalent or ionic bonds
PLeaseeeeeee ANSWERRR
Answer: looks like A
Explanation:
the melting point of gallium metal is 29.76°C If a piece of gallium is sliced into three parts, the melting point will be:
A. higher than 29.76°C
B. 29.76°C
C. lower than 29.76°C
Answer: B. 29.76°C
Explanation:
The melting point is known as an intensive property of matter. This means the melting point is not affected by the amount of mass. Whether the metal is really large or small, the melting point of gallium (Ga) is roughly 29.76 degrees Celsius.
If there are 50 grams of a radioactive element how much will be present after 1,2, and 3 half lifes
Answer:
6.25
Explanation:
The p_______ scale is a color coded scale that identifies acids and bases and neutral substances. Acids are 1-_____ and bases are 8-_____. Neutral substance are ____ like water.
Answer: The pH scale is a color coded scale that identifies acids and bases and neutral substances. Acids are 1-7 and bases are 8-14. Neutral substance are neutral like water.
Explanation:
pH or pOH is the measure of acidity or alkalinity of a solution.
pH is calculated by taking negative logarithm of hydrogen ion concentration.
The pH scale is a color coded scale that identifies acids and bases and neutral substances. The colours from yellow to red indicate an acidic solution, colours blue to violet indicate base and green colour indicates that a solution is neutral.
Acids have pH ranging from 1 to 6.9, bases have pH ranging from 7.1 to 14 and neutral solutions have pH equal to 7. Thus pH scale range from 1 to 14.
Water is neutral with a pH of 7.
What temperature is absolute zero in Fahrenheit?
Answer:
-460 Im pretty sure
Explanation:
The relative number of atoms of a compound can be calculated
by dividing the percentage of an element by the:
Answer:
Obtain the relative numbers of atoms of each element in the compound by dividing the number of moles of each element in the 100 g sample by the number of moles of the element present in the smallest amount.
Answer:
Obtain the relative numbers of atoms of each element in the compound by dividing the number of moles of each element in the 100 g sample by the number of moles of the element present in the smallest amount.
Which order is correct in listing the bond lengths from shortest to longest?
A. single, double, triple
B. triple, double, single
C. single, triple, double,
D. double, triple, single
Answer:
The triple bonds are the strongest and hence the shortest. Then comes double bonds which are of intermediate strength between the triple and single bonds. And finally the single bonds are weaker than the other two.
This way, Triple bonds are the shortest. Then comes double bonds. Finally, single bonds are the longest among the three.
The order of bond lengths is given as,
Triple bond < Double bond < Single bond
please help! you are amazing! also brainliest :)
Which list is in order from biggest to smallest?
A. Universe - Galaxy - Solar system - Earth
B. Earth - Solar system - Nebula - Galaxy
C. Solar system - Galaxy - Nebula - Earth
D. Universe - Earth - Solar system - Nebula
im pretty sure its A if i did all my reasearch right.
hope this helps luv. <3
Answer:
is A
Explanation:
Universe - Galaxy - Solar system - Earth
Brainliest plz
Hope it work
The Earth’s orbit _____.
causes day and night
is a circle
is an ellipse
goes around the moon
Answer:
The Earth's orbit is an ellipse.
Explanation:
The Earth's orbit is not a perfect circle. It is elliptical, or slightly oval-shaped.
Earth's Rotation causes day and night.
The Moon goes around Earth. The Earth goes around the sun.
yrup, USP, is prepared by dissolving 850 g of sucrose in sufficient purified water to make 1000 mL of syrup. Syrup has a specific gravity of 1.31. How many milliliters of water are used to prepare two liters of syrup?
Answer:
920mL of water
Explanation:
To solve this question we need to find as first the mass that must be added of water to make 1000mL of syrup using specific gravity. Thus, we can know the volume of water that mus be added:
1.31 is 1.31g/mL. In 1000mL = 1310g/1000mL. As the mass added of sucrose is 850g, the mass of water = Volume of water is:
1310g - 850g = 460g of water = 460mL to make 1L, To make 2L the amount of water that must be added is:
460mL * 2 =
920mL of waterThe number of milliliters of water are used to prepare two liters of syrup is 920 mL of water.
Given that,
USP, is prepared by dissolving 850 g of sucrose in sufficient purified water to make 1000 mL of syrup. The Syrup has a specific gravity of 1.31.Based on the above information, the calculation is as follows:
1.31 is = 1.31g/mL.
Now
In 1000mL = [tex]1310g \div 1000mL[/tex].
Now if the mass is added so the mass of water should be equivalent to the volume of the water.
= 1310g - 850g
= 460g of water
Now
= 460mL for 1L,
To make 2L the water should be
= 460mL (2)
= 920mL of water
Learn more: brainly.com/question/23334479
How many atoms are in 3.8 mol of calcium? Round your answer to 2 decimal places.
Answer:
[tex]\boxed {\boxed {\sf 2.29 *10^{24} \ atoms \ Ca}}[/tex]
Explanation:
To convert from moles to atoms, we must use Avogadro's Number.
[tex]6.022*10^{23}[/tex]
This number tells us the number of particles (atoms, molecules, ions, etc.) in 1 mole. In this case, the particles are atoms of calcium (Ca).
[tex]6.022*10^{23} \ atoms \ Ca / 1 \ mol \ Ca[/tex]
1. Convert from moles to atoms.
Write Avogadro's number as a fraction.
[tex]\frac {6.022 *10^{23} \ atoms \ Ca} {1 \ mol \ Ca}[/tex]
Multiply the given number of moles of calcium (3.8) by the fraction created.
[tex]3.8 \ mol \ Ca *\frac {6.022 *10^{23} \ atoms \ Ca} {1 \ mol \ Ca}[/tex]
The moles of calcium will cancel.
[tex]3.8 *\frac {6.022 *10^{23} \ atoms \ Ca} {1 }[/tex]
The denominator of 1 is insignifcant and we can turn this into a simple multiplication problem.
[tex]3.8 * {6.022 *10^{23} \ atoms \ Ca}[/tex]
[tex]2.28836*10^{24} \ atoms \ Ca[/tex]
2. Round
The problem tells us to round to 2 decimal places or the hundredth place.
[tex]2.28836*10^{24} \ atoms \ Ca[/tex]
The 8 in the thousandth place tells us to round the 8 to a 9.
[tex]2.29 *10^{24} \ atoms \ Ca[/tex]
There are about 2.29*10²⁴ atoms of calcium in 3.8 moles.
plz help this is due today
Answer:
Explanation:
-
Hello there, I hope you are having a great day Your Question: Which is not an advantage of sexual reproduction? Would be A Diverse Offspring because some could be got to the mother or father carry are mixed together in the offspring.
Jacqueline is interested in helping her overweight cat lose weight so that he will be healthier and more active. She selects a new cat food based on the label’s claim that it can help with weight loss. Jacqueline measures out the food carefully each day, has been weighing the cat every 48 hours, and records the measurement. What keeps this practice from being a scientific experiment? A. There is only one cat and one type of food being used. B. The cat should be weighed every day to collect more data. C. She has not considered whether the cat will like the new food. D. The food is not the brand that Jacqueline’s friend used for his overweight
Answer:
sorry bro / sis this is too long question soo try by yourself
Gases generally have Group of answer choices low density closely packed particles no decrease in volume when pressure is increased no increase in volume when temperature is increased high density
Answer:
Low density
Explanation:
The answer to this question is low density as Gases in general have low densities as their particles are very far apart. Their inter-molecular spaces are actually large. And The number of molecules per unit volume in a gas are small when we put them in comparisons with solids and liquids. That is why they have low densities.
I hope this answers your question.
What type of fish is this?
Answer:
Angel Fish!
Explanation:
Answer:
Angel fish, the other person answered first tho.
Explanation:
please help, its science ->-
Answer:
quantitative
Explanation:
4 Cu2S
How many sulfur atoms are shown?
Answer:
there are 4 sulfur atom.
Question 1/5
Which of the following is not required to define a material as a mineral?
A. useful
B. naturally occurring
C. solid
D. has a crystal structure
Plzzzzz helppppp it’s due already I’ll mark Brainly
What type of energy is caused by positive and negative charges in matter
Answer:
Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged.
Explanation:
10. Name an example of the cause for each of the following:
_a.physical weathering
b.chemical weathering
Answer:
Physical Weathering
Frost wedging. Frost wedging happens when water filling a crack freezes and expands (as it freezes, water expands 8 to 11% in volume over liquid water). ...
Heat/Cold Cycles. ...
Unloading
Explanation:
Chemists once believed that an atom was made of negative electrons dispersed inside a positive mass like raisins in pudding. An experiment with radiation and gold foil demonstrated that most of an atom was
made of empty space. After this experiment, they adopted a new model of the atom that showed the electrons orbiting the nucleus of the atom from a distance. Which of the following statements about the new
model is true?
The new model is perfect and will not change.
The new model is a wrong model and will not last.
The new model fits the data worse than the old model.
The new model fits the data better than the old model.
the new model fits the data better than the old model
The true statement about the new model is the new model fits the data better than the old model. The correct option is b.
What is Rutherford’s gold foil experiment?In Rutherford's gold foil experiment, he discovered that most particles passed through the gold foil, some were distributed in other directions, and very few were redirected back toward the source.
Because all the particles would pass through without being deflected if there was a symmetrical distribution of charges, this experiment proves that the plum pudding model was erroneous.
Rutherford’s gold foil experiment demonstrated how tightly packed the positive charge is within the atom. This was a better experiment.
Thus, the correct option is b. The new model fits the data better than the old model.
To learn more about Rutherford’s gold foil experiment, refer to the below link:
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3.15.8 cm3 of H2SO4 completely neutralised 20 cm3 of NaOH. The NaOH was 1.5 mol/dm3.
The equation is :
2NaOH + H2SO4 -----> Na2SO4 + H2O
Calculate the concentration of the of H2SO4.
Answer:
Molarity = 0.95 mol/dm³
Explanation:
Given data:
Volume of H₂SO₄ = 15.8 cm³
Volume of NaOH = 20 cm³
Concentration of NaOH = 1.5 mol/dm³
Concentration of H₂SO₄ = ?
Solution:
Chemical equation:
NaOH + H₂SO₄ → Na₂SO₄ + H₂O
First of all we will calculate the number of moles of NaOH and for that we will convert the units first,
Volume = 20 cm³/1000 = 0.02 L
Concentration of NaOH = 1.5 mol/dm³
1 mol/dm³ = 1 mol/L
Concentration of NaOH = 1.5 mol/L
Number of moles of NaOH:
Molarity = number of moles / volume in L
1.5 M = number of moles / 0.02 L
Number of moles = 1.5 M ×0.02 L
Number of moles = 0.03 mol
Now we will compare the moles of NaOH and H₂SO₄
NaOH : H₂SO₄
2 : 1
0.03 : 1/2×0.03 = 0.015 mol
Concentration of H₂SO₄:
Volume of H₂SO₄:
15.8 cm³/1000 = 0.0158 L
Molarity = number of moles / volume in L
Molarity = 0.015 mol / 0.0158 L
Molarity = 0.95 mol/L
1 mol/L = 1 mol/dm³
Molarity = 0.95 mol/dm³
In a piece of copper, where would you find the valence electrons?
moving freely between the cations
shared between a cation and anion
attached to a cation
attached to an anion
PLEASE HELP ASAP!!
Answer:
answer is A
Explanation:
just took test
have a good day :)
In a piece of copper, the valence electrons move freely between the cations. Therefore, option (A) is correct.
What are valence electrons?Valence electrons can be defined as the electrons present in the outermost shell of an atom whereas the electrons occupying the inner shell are known as core electrons. Lewis structures can be helpful to evaluate the number of valence electrons and know the types of chemical bonds.
Valence electrons are occupied in different electron shells. These electrons participate in the interaction between atoms and cause the formation of chemical bonds.
Only electrons filled in the valence shell can contribute to the formation of a chemical bond between atoms and decide the reactivity of the element.
The electrons in the piece of copper move freely because the electrons are loosely bound electrons are responsible for the conductivity of the metal. The free movement of electrons in the electron sea is stabilized by the positively charged kernels.
Learn more about valence electrons, here:
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__ is a spark caused when electricity that has built up in a thunderhead discharges
Answer:
Lightning
Explanation:
Lightning is a spark caused when electricity that has built up in a thunderhead discharges.
i) How does the atomic radius change as you go
a) From left to right in a period?
b) Down a group in the periodic table?
Answer:
In general, the atomic radius decreases as we move from left to right in a period and it increases when we go down a group. This is because in periods the valence electrons are in the same outermost shell. The atomic number increases within the same period while moving from left to right which in turn increases the effective nuclear charge.
Explanation:
If they travel 75 meters in 10 seconds, how many meters must they travel each second?
1
What is me velocity
of this new graph?
me rummer roretsUTU Seconds
DIST
25
Answer:
Step-by-step explanation: We are asked to find the distance covered by a man in 15 minutes at a speed of 16 km/hr. 15 minutes = 15/60 hour. Therefore, the person can run 4 km in 15 minutes.
Explanation:
The total number of the elements above with 2 valence electron is ____.
Answer:
four elements
Explanation:
He = 1s²
Be = 1s² 2s²
C = 1s² 2s² 2p²
Mg = 1s² 2s² 2p⁶ 3s²
Si = 1s² 2s² 2p⁶ 3s² 3p²
Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Valence electrons are those electrons which are present in outer most electronic shell.
He, Be, Mg, Ca these four elements have 2 valence electrons.
While Si and C have four valance electrons.
The total number of the elements above with 2 valence electron is four.
The electronic configurations of the elements are given:
He = 1s²
Be = 1s² 2s²
C = 1s² 2s² 2p²
Mg = 1s² 2s² 2p⁶ 3s²
Si = 1s² 2s² 2p⁶ 3s² 3p²
Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Valence electrons are those electrons which are present in outer most electronic shell.
He, Be, Mg, Ca these four elements have 2 valence electrons.Learn more:
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If a concentrated solution of acetic acid is 99.5 % HC 2 H 3 O 2 and has a density of 1.05 g/mL, what is the concentration of this acid in moles per litre?
The concentration of this acid in moles per litre : 17.41
Further explanationGiven
99.5% acetic acid
density=ρ=1.05 g/ml
Required
the concentration (mol/L)
Solution
99.5% dan density 1.05 g/ml (MW acetic acid = 60 g/mol)
[tex]\tt 99.5\%\times 1.05\dfrac{g}{ml}\times \dfrac{1000~ml}{L}=1044.75~g/L\\\\\dfrac{1044.75~g/L}{60~g/mol}=17.41~mol/L[/tex]
