All of the halogens __________. a. exhibit metallic character b. form salts with alkali metals with the formula mx c. exist under ambient conditions as diatomic gases d. tend to form negative ions of several different charges e. tend to form positive ions of several different charges

Answer:

Explanation:

To determine if the bock will float you need:

The block has 3 dimmentions: lenght, wide and height, its volume is:

[tex]V=wide*lenght*height[/tex]

Once calculated it and measured the  weight, you calculate the density:

[tex]\rho=\frac{m}{V}[/tex]

If the density of the block is smaller than the density of water (arroung 1000 kg/m3) the block will float.

Final answer:

Chemical reactions are classified into various types like combination, decomposition, single replacement, double replacement, combustion, acid-base, precipitation, and redox reactions. Physical changes differ from chemical changes in that they do not alter the substance's composition. Chemical changes can be indicated by observable phenomena like color change or formation of a precipitate.

Explanation:

Chemical reactions are processes where reactants transform into products with different properties. In chemistry, reactions are classified into combination, decomposition, single replacement, double replacement (exchange reactions), combustion, acid-base reactions, precipitation reactions, and oxidation-reduction (redox) reactions. These are the basic models used to describe how atoms and molecules interact during chemical changes.

Understanding Physical and Chemical Changes

It's important to note the difference between physical changes, which are changes in the state or appearance of a substance that do not affect its chemical composition, and chemical changes that result in new substances with different properties. Indications of a chemical change may include a color change, temperature change, emission of light, formation of bubbles, or formation of a precipitate. Generally, chemical changes are more difficult to reverse when compared to physical changes.

Common Examples of Chemical Reactions

Examples of these reaction types include the formation of water from hydrogen and oxygen (combination), the breakdown of hydrogen peroxide to water and oxygen (decomposition), the replacement of silver in a compound by copper (single replacement), the formation of sodium chloride from the reaction of hydrochloric acid and sodium hydroxide (acid-base neutralization), and the rusting of iron (redox).

It is true that carbon dioxide can transition from solid to gas directly through sublimation, as seen with dry ice at -78.5°C.

The statement that carbon dioxide can change directly from the solid phase to the gaseous phase is true. This process is known as sublimation. Solid carbon dioxide, also known as dry ice, undergoes sublimation at a temperature of approximately -78.5°C under 1 atmosphere of pressure, transitioning directly from a solid to a gas without passing through the liquid phase. According to the phase diagram of CO₂, the substance cannot exist as a liquid under ambient pressure conditions because its triple point is well above 1 atm. Instead, when warmed, solid CO₂ sublimes, turning directly into a gas.

Answer:

1: atomic number is 26

2: number of valence electrons is 2

3: number of orbits is 4

4: atomic mass is 56

5: number of neutrons is 30

6: number of electrons in n=3 is 14

Explanation:

Final answer:

A main-group element's lettered group number is closely linked to its valence electrons, with groups 1 and 2 matching the group number and groups 13 to 18 having valence electrons equal to the group number minus ten. Transition metals, found in groups 3-12, do not follow this rule and can have variable valences.

Explanation:

The relationship between a main-group element's lettered group number and its valence electrons is direct and predictable. For elements in groups 1 and 2 (the alkali metals and alkaline earth metals, respectively), the group number is equivalent to the number of valence electrons. For example, elements in group 1 have one valence electron, while those in group 2 have two valence electrons.

When looking at groups 13 to 18, the number of valence electrons is equal to the group number minus ten. Thus, elements in group 13 have three valence electrons, whereas elements in group 14 have four, and so on, with the noble gases in group 18 having eight valence electrons. This relationship helps to determine the chemical properties and reactivities of the elements as they tend to react to achieve a full outer shell of valence electrons, akin to the stable electron configuration of noble gases.

However, this relationship does not apply to the transition metals (groups 3-12), as they may have variable valences. These metals often exhibit multiple possible charges and are identified using Roman numerals in their compound names, such as iron (III) chloride.

In an atom, the number of neutrons determines most specifically the isotopes of an element.

Keywords: Atom, sub-atomic particles, electrons, protons, neutrons, isotopes  

Level: High school

Subject: Chemistry  

Topic: Atomic structure

In an atom, the number of neutrons determines most specifically the [tex]\boxed{{\text{isotopes}}}[/tex].

Further Explanation:

The smallest component of an element and the building block of matter is known as an atom. It is made up of a central part which is called atomic nucleus. It contains protons and neutrons in it. Nucleon is a collective term that is used for both protons and neutrons. Electrons revolve around the nucleus in definite circular paths called orbits. Protons are the subatomic particles having a positive charge whereas neutrons do not carry any charge. Electrons are negatively charged subatomic particles. An atom is usually denoted as [tex]_{\text{Z}}^{\text{A}}{\text{X}}[/tex], where X is the element symbol, Z is the atomic number and A is the atomic mass or mass number.

Atomic number indicates the total number of protons present in the nucleus of an atom. In other words, the total positive charge in the atomic nucleus is known as the atomic number. The total number of nucleons present in the atomic nucleus is known as the atomic mass.

The atoms of the same element that has the same atomic number but different atomic masses are called isotopes. For example, [tex]_{\text{6}}^{{\text{11}}}{\text{C}}[/tex] and [tex]_{\text{6}}^{{\text{12}}}{\text{C}}[/tex] are isotopes. Both these atoms belong to the carbon element so these have the same atomic number (6) and therefore the number of protons is the same in both. For a neutral atom, the number of electrons is equal to the number of protons so these have the same number of electrons also. The only difference in these is the number of neutrons which is different in both isotopes. [tex]_{\text{6}}^{{\text{11}}}{\text{C}}[/tex] has 5 neutrons while there are 6 neutrons in [tex]_{\text{6}}^{{\text{12}}}{\text{C}}[/tex].

Therefore, the number of neutrons determines the isotopes of an element.

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Answer details:

Grade: Senior School

Chapter: Atomic structure

Subject: Chemistry

Keywords: atom, element, matter, atomic nucleus, electrons, protons, neutrons, subatomic particle, A, X, Z, atomic number, positive charge, orbits, circular paths, isotopes.

Answer:

Law of definite proportion

Explanation:

A compound is a substance which is composed of two or more elements. According to the law of definite proportion, a compound is made up of element in definite and fixed ratio (by mass) therefore elements in compounds comprises of fixed percent. This law was given by English chemist john Dalton in 1808.

I believe that the correct answer among the choices is:

D. The proportion of each element will remain constant, no matter how large or small the volume.

The proportion of the elements is an inherent property of a compound. It can never be changed no matter the size of the compound. This is because the elements are linked by chemical bonds.

Answer: The correct answer is image 1 shows a monomer, and Image 2 shows a polymer.

Explanation:

A monomer is defined as the molecule that react with the same molecule to form a large molecule known as polymer. These are the repeating units in a polymer.

A polymer is a large molecule which are formed when a large number of  same type of molecules react together.

A macro-molecule is defined as a very large molecule such as proteins which are formed by the polymerization of monomers. They are known as natural polymers.

A synthetic polymer are defined as the polymers which are made by humans. They are known as artificial polymers.

In the images given, Image 1 represents a monomer known as ethylene and Image 2 is a polymer known as polyethylene.

Hence, the correct answer is image 1 shows a monomer, and Image 2 shows a polymer,

Answer:the answer is B

Explanation: did the test

IE1 = 578 kJ/mol 

IE2 = 1820 kJ/mol 

IE3 = 2750 kJ/mol 

IE4 = 11600 kJ/mol

If the following set of successive ionization energies are your ionization values this would likely belong to Aluminum. Since there is a huge point between the third and fourth ionization energies, which designates that the atom reached noble gas configuration after the third electron was removed. The element which has 3 valence electrons in the third period is aluminum.

According to the concept of emission spectrum, when an electron looses energy it releases a photon of equivalent energy.

Emission spectrum is defined as a spectrum of a chemical compound or substance composed of frequencies of electromagnetic radiation. Radiations which are emitted while electron make transition from higher to lower energy level.

Energy of photon is equal to the difference between the two energy states . There are many possible electronic transitions in an atom and every transition has a specific wavelength.

Collection of different transitions with respect to different wavelengths makes up an emission spectrum.Emission spectrum of each element is unique and therefore spectroscopy is used to identify elements which are present in different substances.

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one is air and the other is a liquid 

Final answer:

Dicing potatoes is a physical change since it alters their shape and size but not their chemical identity. This kind of physical change, while being irreversible, does not transform the potatoes into a new substance.

Explanation:

Dicing potatoes is indeed a physical change. This is because when you dice potatoes, you are only changing their shape and size, not their chemical structure or identity. Physical changes can be reversible or irreversible, but they do not alter the fundamental identify of a substance.

Some examples of reversible physical changes include melting, where ice changes to liquid water and can be refrozen, and dissolving, such as when salt is dissolved in water and can be recovered by evaporating the water. Conversely, irreversible physical changes do not easily revert to the original form, such as cutting hair—once it is cut, it cannot grow back instantly.

In the case of dicing potatoes, the physical change is irreversible as you cannot restore the potatoes to their original, uncut state. However, the potatoes remain chemically identical before and after dicing.

Answer:

Sulfur ₁₆S³²

Explanation:

The sulfur have sixteen protons sixteen neutrons and sixteen electrons. The sum of neutrons and protons is equal to atomic mass. So the given element have sixteen protons and sixteen electron, the atomic mass would be 32 and the element with atomic mass 32 is sulfur.

The number of electrons are equal to the number of protons. In the given element two electrons are more than number of protons. It means element gain two extra electron from another element and it is present in ionic form.

It is present in given form:

S²⁻

Electronic configuration:

S₁₆ = [Ne] 3s² 3p⁴

To complete the octet sulfur gain two electrons from other element and get stable.

Answer:

[tex]^{32}_{16}S^{2-}[/tex]

Explanation:

Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.

However, when we talk about the atomic number of the ion, it is not equal to the number of electrons as electron can be gained or loosed.

This is why, more appropriately, the number of the protons which are present in the nucleus of the atom is called the atomic number.

Thus, number of protons = atomic number = 16

The element must be sulfur.

Since, number of protons is not equal to the number of electrons, thus the isotope will not be neutral.

There are 2 more electrons than the number of protons and thus, the isotope will be having a charge of -2.

Mass number is the number of the entities present in the nucleus which is the equal to the sum of the number of protons and electrons.

Mass number = Number of protons + Number of neutrons  = 16 + 16 = 32 neutrons

The identity is:- [tex]^{32}_{16}S^{2-}[/tex]

The answers to the mole-atom and mole-mass conversions are as follows:

Mole-atom questions can be calculated using the following expression;

no. of atoms = no. of moles × 6.02 × 10²³

QUESTION 1:

Number of moles in Zinc is calculated as: 1.55 x 10²⁷ atoms ÷ 6.02 × 10²³

= 2.6 × 10³ moles of Zinc.

QUESTION 2:

The number of atoms in 25 moles of Calcium is 25 × 6.02 × 10²³

1.51 × 10²⁵ atoms of Ca.

QUESTION 3:

The number of atoms in 0.35 moles of carbon (C) is 0.35 × 6.02 × 10²³

2.11 × 10²³ atoms of C

QUESTION 4:

The number of moles in 7.6 x 10²⁴ atoms of Helium is 7.6 × 10²⁴ ÷ 6.02 × 10²³

= 1.26 × 10¹ = 12.6moles of He.

QUESTION 5:

The number of moles in 28.0 grams of oxygen is 28g ÷ 16g/mol = 1.75mol

QUESTION 6:

The mass of 5.0 moles of Iron (Fe) is 5moles × 56g/mol = 280g

QUESTION 7:

The number of moles of argon in 452g of argon is 452g ÷ 39.9g/mol = 11.33mol

QUESTION 8:

The grams in 16.5 mol of hydrogen is 16.5mol × 1 = 16.5grams.

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1.Nitrogen

7  .Carbon

3.Oxygen

5.Hydrogen

Explanation: I took the test

To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, the chemical formula for artificial sweetener is C[tex]_7[/tex]H[tex]_5[/tex]NO[tex]_3[/tex]S.

Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.

In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.

The chemical formula for artificial sweetener is C[tex]_7[/tex]H[tex]_5[/tex]NO[tex]_3[/tex]S.

The number of atoms of Carbon is 7.

The number of atoms of Hydrogen is 5.

The number of atoms of Nitrogen is 1.

The number of atoms of oxygen is 3.

The number of atoms of sulfur is 1.

Therefore, the chemical formula for artificial sweetener is C[tex]_7[/tex]H[tex]_5[/tex]NO[tex]_3[/tex]S.

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Answer:

Intravenous injection.

Explanation:

Injections are the needle used for the transfer of chemicals or drugs from outside environment directly in to the body of an individual. Different body regions are used to inject different drugs depending on their function and mode of action.

Intravenous injections are the needles used to inject the drug directly into the blood stream in the veins and in the muscles. This intravenous injection prevents the over dosage of drugs and proves quite effective in its function.

Thus, the answer is intravenous injection.

First let us calculate the initial molarity of the 2.45 L of solution. Molar mass = 171.34 g/mol

moles Ba(OH)2 = 74.28 g * (1 mole / 171.34 g) =  0.4335 moles

Molarity (M1) = 0.4335 moles / 2.45 L = 0.177 M

Now using the formula M1V1 = M2V2, we can calculate how much to dilute (V1):

0.177 * V1 = 0.1 * 1

V1 = 0.56 L

Therefore 0.56 L of the initial solution must be diluted to 1 L to make 0.1 M

The Net Ionic equation for the reaction between MgSO4 with Sr(NO3)2 is given by;  

Sr ⁺²(aq) + SO₄⁻²(aq) → SrSO₄(s)

That is:

MgSO₄(aq) + Sr(NO₃)₂(aq) → Mg(NO₃)₂(aq) + SrSO₄(s)

Therefore; the ionic equation required will be;

Sr ⁺²(aq) + SO₄⁻²(aq) → SrSO₄(s)

Level: High school

Subject: Chemistry

Topic: Chemical equation

Sub-topic: Net ionic equations

A star is a celestial object made of gas that radiates light and heat due to the fusion of hydrogen nuclei into helium. Not all celestial objects are stars; for example, brown dwarfs are too 'cool'. Stars exist in various stages including protostars (stars in formation) and planetary nebulas (stars near the end of their lifecycle).

A star is a celestial object made of gas that radiates light and heat. This radiation is due to the fusion of hydrogen nuclei into helium, a process that engaged throughout much of a star's lifetime. Stars are a central object found in space and form an integral component of galaxies, including our very own Milky Way.

However, not all celestial objects that emit light and/or heat are stars. For instance, Spectral Classes L, T, and Y comprise objects that are too cool to be considered stars because they don't possess the necessary heat for hydrogen fusion to occur. These are often called brown dwarfs.

Stars exist in a variety of stages and forms. For instance, A Planetary Nebula is a stage of a star near the end of its lifecycle, during which it ejects a shell of gas that expands away from the star. On the other hand, Protostars are stars in their formation stage. These objects often emit infrared radiation due to being embedded in an envelope of dust and gas.

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