The smallest and the basic particle of a chemical element is said to be an atom. It is made up of three subatomic particles that is electrons, protons and neutrons. The neutrons and protons are present in the nucleus of an atom whereas electrons are present in the orbits around the nucleus of the atom. There are several shells in the orbital depending on the atomic number. The electrons which are present in the outermost shell are said to be valence electrons.
They can be determined by the electronic configuration of the element.
The atomic number of strontium, [tex]Sr[/tex] is 38. The electronic configuration of strontium, [tex]Sr[/tex] is:
[tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}[/tex]
From the electronic configuration it is clear that the outermost shell of strontium, [tex]Sr[/tex] is [tex]5s[/tex]. So, the number of valence electrons in strontium, [tex]Sr[/tex] is 2.
Hence, there are 2 valence electrons in an atom of strontium ([tex]Sr[/tex]).
The number of valence electrons are in an atom of strontium (Sr) is 2 and the correct option is option B.
Atomic number is the number of protons present in the nucleus of an atom. It is always equal to the number of electrons in orbit about that nucleus (in a nonionized atom). Thus, all atoms that have the same number of protons--the atomic number--are atoms of the same element.
The modern periodic table is arranged in such a way that all the elements have an increasing atomic number, and subsequently, increasing mass number.
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What is the mass of a sample of aluminum that absorbs 596 J of heat when the temperature is raised from 30.0°C to 100.1°C? Specific heat of aluminum = 0.900 J/g oC
Answer is: the mass of a sample of aluminum is 9.45 grams.
ΔT = 100.1°C - 30.0°C.
ΔT = 70.1°C.; change in temperature of a sample of aluminium.
Cp(Al) = 0.900 J/g·°C; specific heat capacity for aluminium.
Q = 596 J; heat absorbed.
Q = m(Al) · ΔT · Cp(Al).
m(Al) = Q ÷ (ΔT · Cp(Al)).
m(Al) = 596 J ÷ (70.1°C · 0.900 J/g·°C).
m(Al) = 9.45 g; mass of aluminium sample.
3. Classify each of the following materials as a pure substance or mixture. If it is a pure substance, indicate if it is an element or a compound. If it is a mixture, indicate if it is a homogeneous mixture or heterogeneous. (2 points each)
Questions
1.
The copper in a copper wire
2.
Gatorade
3.
Chocolate chip ice cream
4.
Sugar (C12H22O11)
5.
Glitter nail polish
6.
Diamond (C)
7.
Salt (NaCl)
8.
Air
9.
Helium gas
10.
Carbon dioxide gas
11.
Coffee
12.
Caffeine (C8H10N4O2)
13.
Tomato soup
14.
Chicken noodle soup
15.
Brass
16.
Pure water
17.
Pure iron
18.
Sweat
19.
Baking soda (NaHCO3)
Classify each of the following materials as a pure substance or mixture. If it is a pure substance, indicate if it is an element or a compound. If it is a mixture, indicate if it is a homogeneous mixture or heterogeneous. (2 points each)
Questions
1.
The copper in a copper wire pure
2.
Gatorade heterogeneous
3.
Chocolate chip ice cream heterogeneous
4.
Sugar (C12H22O11) pure
5.
Glitter nail polish heterogeneous
6.
Diamond (C) pure
7.
Salt (NaCl) pure
8.
Air homo
9.
Helium gas pure
10.
Carbon dioxide gas pure
11.
Coffee depends on being black and unsaturated
12.
Caffeine (C8H10N4O2) pure
13.
Tomato soup heterogeneous
14.
Chicken noodle soup heterogeneous
15.
Brass homo
16.
Pure water pure
17.
Pure iron pure
18.
Sweat homo
19.
Baking soda (NaHCO3) pure
Final answer:
Detailed classification of substances as pure substances or mixtures, elements or compounds, and homogeneous or heterogeneous mixtures.
Explanation:
A pure substance either consists of a single type of atom, an element, or of molecules made from atoms of two or more types bound together, known as compounds. Mixtures can be either homogeneous, where the composition is consistent throughout, or heterogeneous, where the substances that make up the mixture are not evenly distributed. The items can be classified as -
1. The copper in a copper wire: Pure substance - Element
2. Gatorade: Mixture - Homogeneous
3. Chocolate chip ice cream: Mixture - Heterogeneous
4. Sugar (C12H22O11): Pure substance - Compound
5. Glitter nail polish: Mixture - Heterogeneous
6. Diamond (C): Pure substance - Element
7. Salt (NaCl): Pure substance - Compound
8. Air: Mixture - Homogeneous
9. Helium gas: Pure substance - Element
10. Carbon dioxide gas: Pure substance - Compound
11. Coffee: Mixture - Homogeneous
12. Caffeine (C8H10N4O2): Pure substance - Compound
13. Tomato soup: Mixture - Homogeneous
14. Chicken noodle soup: Mixture - Heterogeneous
15. Brass: Mixture - Homogeneous
16. Pure water: Pure substance - Compound
17. Pure iron: Pure substance - Element
18. Sweat: Mixture - Homogeneous
19. Baking soda (NaHCO3): Pure substance - Compound
Which of these four liquids is a mixture, made up of parts, some of which can be separated by flirtation? a. Salt water b. Skimmed milk c. Orange juice with pulp d. Distilled water
Orange juice with pulp is the correct answer because it is a heterogeneous mixture with suspended particles that can be separated by filtration.
Explanation:The question asks to identify which of the four liquids listed is a mixture that can be separated by filtration. Among the options provided:
Salt water is a homogeneous mixture, known as a solution, where the salt is completely dissolved in the water and cannot be separated by filtration.Skimmed milk is a colloid where the particles are larger than those in a solution but remain dispersed and do not settle, and thus also cannot be easily separated by filtration.Orange juice with pulp is a heterogeneous mixture that has suspended particles (pulp) which can be separated through filtration.Distilled water is not a mixture at all but a pure substance with a uniform and definite compositionTherefore, the liquid that is a mixture and can have some of its parts separated by filtration is orange juice with pulp.
Electron configuration for Lithium.
The answer to problem is [He] 2s1. Hope it helps
Your answer is [He] 2s1
Hope that helps :)
Read the scenario.
A lizard is at an initial position of 2 m and walks to a position of 10 m in 4 s.
What is the lizard’s average velocity?
2.5 m/s
-3 m/s
2 m/s
3 m/s
The answer is C. 2 m/s
Answer: 2m/s
Explanation:
Initial position = 2m
Final position = 10m
Distance = 10-2 = 8m
Time = 4s
Velocity = distance(m) /time(s)
Velocity = 8/4 = 2m/s
Out of the following, which element has properties of both metal and nonmetal?
A.
Ce
B.
Be
C.
Te
D.
Ne
A fertilizer is 60.9% ammonium phosphate. What is the percent P in the sample? Answer in units of %
I originally got 20.7685% but it says my answer is wrong. Help?
Answer:- 12.7%
Solution:- It says, ammonium phosphate is 60.9%. It means if we assume 100 g of the sample then there is 60.9 g ammonium phosphate in it.
Formula of ammonium phosphate is [tex](NH_4)_3PO4[/tex] and it's molecular weight is 149 grams per mol. There is only one P in the formula and so the mass of P in 149 g of ammonium phosphate is 31 g(atomic mass of P).
Now, we could use the proportions to find out the mass percentage of P in the sample.
31 g P is present in 149 g of ammonium phosphate, how many grams of P would be present in 60.9 g of ammonium phosphate. Let's set the proportions as:
[tex]\frac{31}{149}=\frac{x}{60.9}[/tex]
[tex]x=\frac{31(60.9)}{149}[/tex]
[tex]x=12.7[/tex]
This 12.7 g of phosphorous is present in 100 g of the sample means there is 12.7% phosphorous in the sample.
how are ionic bonds formed? a. by the disintegration of one or more electronsb. by the sharing of one or more electrons between two atomsc. by the transfer of one or more electrons from one atom to anotherd. by the disintegration of one or more protons
The correct answer is: by the transfer of one or more electrons from one atom to another.
The requirements of atoms to be able to participate in hydrogen bonding with a hydrogen atom include
all of the following except
A. atoms must have one lone pair of electrons.
B. atoms must be electronegative.
C. atoms must be small.
D. atoms must not be able to closely approach the hydrogen.
Answer: C. atoms must be small.
Explanation: Hydrogen bond is the result of the electrostatic forces of attraction between the hydrogen and the electonegative atom. It is a type of dipole dipole interaction which is not so much of a covalent bond.
The options A, B and D satisfies the definition of the hydrogen bonding but the option C seems to be irrelevant as hydrogen bonding does not deal with the size of the atom.
Thus for the hydrogen bonding , the other atom must be electronegative, and atoms must have atleast one lone pair of electrons and atoms must not be able to closely approach the hydrogen.
Which is a raw material necessary for photosythisies.
water and carbon dioxide
50 POINTS!!! Based on your observations in the virtual lab, fill in the data table below.
Question 2 options:
Separated using a filter; magnetism
Separated using a magnet; malleability
Separated using filtration; conductivity
Separated using a magnet; magnetism
Hi Khal75,
Experiment: How to seperate iron fillings
Iron fillings is a substance that attracts to magnets.
Answer - Separated using a magnet; magnetism
If you move a magnet around different solids with the iron fillings in it, it wil attract the iron to be able to seperate it.
What element is most likely to form a diatomic molecule?
A.
Cr
B.
K
C.
Br
D.
Ga
Energy transformations that occur when a ball is thrown in the air
How can affluence help us to solve environmental problems?
Most people like to go outside on a sunny day, but too much sun exposure can cause sunburns as well as long term health problems, such as eye damage or skin cancer. How do humans protect themselves from too much sun exposure?
Answer:
all of these
Answer:
all of these
Explanation:
Select all that apply to physical and chemical properties. The various components of a mixture do not combine chemically. Chemical properties can only be observed during a chemical reaction. The rusting of iron is a chemical reaction. Melting and boiling points are physical properties. Mass and volume are chemical properties.
Explanation:
A property that does no change the chemical composition of a substance are known as physical properties.
For example, mass, volume, size etc are all physical properties.
Whereas a property that changes the chemical composition of a substance are known as chemical properties.
For example, reactivity, toxicity etc are all chemical properties.
Therefore, identifying the given statements as follows.
The various components of a mixture do not combine chemically - physical property.Chemical properties can only be observed during a chemical reaction - chemical property.The rusting of iron is a chemical reaction - chemical property.Melting and boiling points are physical properties - physical property.Answer:
The various components of a mixture do not combine chemically - physical property.
Chemical properties can only be observed during a chemical reaction - chemical property.
The rusting of iron is a chemical reaction - chemical property.
Melting and boiling points are physical properties - physical property.
Explanation:
Which of the following by hypotheses cannot be tested using the scientific method?
1 . If the temperature is increased , the reaction rate of HCI AND NaOH will increase.
2.Cold weather causes car tires to deflate .
3. The booing of Hiroshima ending world war ll.
4. If students do more homework their grades will improve.
What is true of valence electrons?
Question 14 options:
They exist in the outer orbital.
They have difficulty moving from one orbital to another.
They are always the lowest energy electrons of the atom.
They easily move from one orbital to anothe
Answer:They exist at specific energy levels.
Explanation:
Express in scientific notation. Choose the answer with the proper number of significant figures. (3 x 104) (4 x 1023) = _____ 1227 12 x 1027 10 x 1027 1 x 1028
You know what number of significant figures is required by what they give you originally. In this case, there is only one. (3x10^4)(4x10^23) = 1.2x10^28. However, this is the answer with two significant figures. Thus, round it to become one sigfig: 1x10^28.
Answer:
1x10^28
Explanation:
Which one of the following mixtures is classified as a suspension
Final answer:
A suspension is a heterogeneous mixture where the dispersed particles are large enough to settle upon standing. Mud in water is an example of a suspension because it has large particles that are visible, the mixture is cloudy, and particles settle when undisturbed.
Explanation:
To identify which mixture is classified as a suspension, it's essential to understand the particle sizes involved in different mixtures. A suspension contains particles with diameters around 1 µm (1000 nm) that are dispersed throughout another phase. Examples of suspensions include muddy water and paint. In contrast, colloids involve much smaller particles (2 to about 500 nm in diameter) that do not settle on standing, such as milk or fog.
Considering the information provided, a suspension is a heterogeneous mixture where the dispersed particles are large enough to settle out upon standing. These particles can often be separated from the dispersing medium by filtration. In contrast, a solution has much smaller particles that do not settle and cannot be filtered out.
From the examples provided, mud in water fits the definition of a suspension. The particles are of appropriate size, it's heterogeneous, the mixture is cloudy due to the particles, and it will allow for settling over time if left undisturbed.
which of the following is a physical property?
a) letting milk turn sour
b) allowing silver to tarnish
c) burning wood
d) melting ice
plz explain why too so i can actually learn it!!
As you pass a magnet over a blackish-yellow powder on a glass plate, black particles separate from the powder and become attached to the magnet. After a few passes of the magnet over the powder nothing but a yellow powder remains in the glass plate. The original blackish-yellow powder was:
AS given that we have started with a solid powder on a glass plate which appears to be blackish yellow, on passing magnet the black particles separated.
so the black particles are magentic in nature. however the yellow portion of powder is not magnetic or diamagnetic
so its clear that we are able to separate the black and yellow portions by simple physical methods.
If we are able to separate any two substances by simple physical methods then it means that the powder is a mixture and not a compount
What is the molarity of 820 ml of kl solution that contains 36.52 g of kl
The formula is molarity (M) = moles / liters
molarity (M) = ?
1/ mass = 36.52 g of KCl (you need to find the mole)
mole = mass / Molar mass
Molar mass of KCl:
K = 39.10 g/mol
Cl = 35.45 g/mol
Add K and Cl together: 39.10 + 35.45 = 74.55 g/mol
mole = 36.52 g of KCl / 74.55 g/mol
mole = 0.489 mol of KCl
2/ Volume = 820 mL ( you need to convert to L)
820 / 1000 = 0.82 L
=> M = mol / L
M = 0.489 mol / 0.82 L
M = 0.59 mol/L
Hope this help!
Answer: 0.27 M
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
n = moles of solute
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{36.52g}{166g/mol}=0.22moles[/tex]
[tex]V_s[/tex] =volume of solution in ml
Molarity =[tex]\frac{0.22\times 1000}{820ml}=0.27M[/tex]
The molarity of the solution is 0.27 M.
Protons are positively charged and repel other protons. Which order particle is found in the nucleus and separates protons so that the strong force can hold the nucleus together?
How do you turn a proportionality between variables into an equation?
Answer. By adding the proportionality constant .
Explanation:
suppose 'x' a is directly proportional to the 'y' , where x and y are variables:
x ∝ y
with an input of constant value 'K' proportionality relation gets converted into an equation:
x = K y
For example : Gravitational force is directly proportional to the product of two masses and inversely proportional to the square of the distance between the two masses.
F ∝ [tex]\frac {m_1m_2}{r^{2}}[/tex]
To convert this proportionality relation constant 'G' was introduced known as gravitational constant whose value remains constant under every conditions.
[tex]F=\frac {G\times m_1m_2}{r^{2}}[/tex]
[tex]G=6.67408\times 10^{-11}m^3Kg^{-1}s^{-2}[/tex]
Which characteristics make Mercury different from Earth? Check all that apply. Rings no moon slow revolution hot surface temperatures atmosphere of carbon dioxide
Mercury is different from the Earth for the following reasons:
Mercury has no moon and hot surface temperatures.
Mercury is the smallest planet and the first planet from the sun. Mercury has no atmosphere. The surface temperature of Mercury is incredibly hot, the side of the planet facing the sun has a temperature of 800 degrees F.
Mercury and the earth are the planets of the solar system. Mercury has no moon and has a hot surface temperature. Thus, options b and d are correct.
What is a planet?A planet is a celestial body that revolves around the sun and rotates on its axis in its orbitals. They are different from fixed stars like the sun and moon in having movements. Mercury is the first and the closest planet to the sun.
Being closest to the sun it has more surface temperature than earth and is very small. It lacks an atmosphere as compared to earth and has no natural satellite like the moon that revolves around it.
Therefore, mercury lacks a moon and has a high surface temperature.
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Answer File Below!
If many observations or results of experiments fail to agree with your deductive reasoning, then:
the general principle or theory is probably false.
the general principle or theory is probable true.
the general principle or theory is probably false
12. What volume of carbon dioxide contains the same number of molecules as 20.0 mL of oxygen at the same conditions?
What is the energy of a photon of green light whose frequency is 6.85 X 1014/seC?
I would be very thankful if I can receive the answer fast
Frequency of photon = is 6.85 X 10¹⁴ sec⁻¹
Energy of photon , E = hv
where h is Planck's constant, v is the frequency of photon
E = 6.63 × 10⁻³⁴ J.s x 6.85 X 10¹⁴ s⁻¹
E = 4.54 x 10⁻¹⁹ J
Therefore, the energy of a photon of green light is 4.54 x 10⁻¹⁹ J.