CHEMISTRY HIGH SCHOOL

What is the correct formula for calcium fluoride? a. caf2 b. caf c. ca2f d. ca2f2

Answers

Answer 1
Answer: A) CaF2 is the correct formula

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MIDDLE SCHOOL

Atoms of metallic elements tend to...

Answers

The answer is: lose electrons and form positive ions.

Most metals have strong metallic bond, because of strong electrostatic attractive force between valence electrons (metals usually have low ionization energy and lose electrons easy) and positively charged metal ions.

The ionization energy (Ei) is the minimum amount of energy required to remove the valence electron, when element lose electrons, oxidation number of element grows (oxidation process).

For example, magnesium has atomic number 12, which means it has 12 protons and 12 electrons. It lost two electrons to form magnesium cation (Mg²⁺) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.  

Electron configuration of magnesium ion: ₁₂Mg²⁺ 1s² 2s² 2p⁶.  

COLLEGE

Give a reason why each of the following statements is a safe prediction:(a) Every compound of Rb with a nonmetal is ionic in character.(b) Every compound of nitrogen with a halogen element is a molecular compound.(c) The compound MgKr2 does not exist.(d) Na and K are very similar in the compounds they form with nonmetals.(e) If contained in an ionic compound, calcium (Ca) will be in the form of the doubly charged ion, Ca2+.

Answers

Calcium is a member of group two hence it is divalent therefore it will always form of the doubly charged ion, Ca2+.

We shall now answer the questions individually;

1) All the compounds of Rb with nonmetals are ionic because Rb is highly electropositive and easily donates electrons to nonmetals.

2) Every element of nitrogen with a halogen is molecular because both nitrogen and halogens are nonmetals hence the compounds are formed by covalent bonding.

3) The compound MgKr2 does not exist because Kr is a noble gas and does not react with other elements.

4) Na and K are very similar in the compounds that they form because they belong to the same group in the periodic table.

5) Calcium is a member of group two hence it is divalent therefore it will always form of the doubly charged ion, Ca2+.

Learn more about ionic compounds: brainly.com/question/731147?

Answer:

See explanation

Explanation:

a) An ionic bond is a bond that is created by the electrostatic attraction between a negative and a positively charged ion. Binding is only possible between atoms with a large difference in electronegativity.  These are bonds between atoms with a metal character and atoms with a non-metal character. Rb is a positive charged metal. Together with a non-metal it will make an ionic bond, because the electronegativity is big enough.

b) Nitrogen is a diatomic molecule in the VA family on the periodic table. Nitrogen has five valence electrons, so it needs three more valence electrons to complete its octet. A nitrogen atom can fill its octet by sharing three electrons with another nitrogen atom, forming three covalent bonds, a so-called triple bond.

Covalent bonds are chemical bonds in which two or more elements join together by sharing electrons, rather than transferring electrons, as is the case with ionic bonds. ... These elements are considered to be covalent. Other elements that can form covalent bonds include nitrogen, carbon and fluorine.

c) MgKr2 does not exist because magnesium ( Mg2+) has 2 valence electrons. This means it will bind with 2 atoms with 7 valence electron ( like Cl- and form Mgcl2) or with 1 atom with 6 valence electrons ( like oxygen and form MgO). This to form a stable noble gas configuration. Since Kr is a noble gas it already has 8 valence electrons and is already stable, so 2 Kr atoms cannot bind on Magnesium. MgKr2 does not exist.

d) Na and K are both part of the alkali group, this means they have only 1 valence electron. Since the most non-metals have 6 or 7 valence electrons, they will bind on the same way. Both are also part of the s-block.

e) Calcium is a positive charged metal. IT will bind to a negative charged non-metal to form an ion bond.  Calcium is in group 2, so it has 2 valence electrons. This means it will appear as Ca2+.

An example CaBr2. Br has 7 valence electrons. So 2 Br atoms will bind on Calcium since it's in its form Ca2+, where are 2 valence electrons.

MIDDLE SCHOOL

Burt's mother asked him to use a spoon to stir the stew that was cooking on the stove. Which spoon will stay the coolest while he stirs and why? Question 9 options:

An aluminum spoon because it can only be heated by radiation.


An iron spoon because it is a strong conductor of heat.


A wooden spoon because it is an insulator.


A silver spoon because it is an insulator.

Answers

Metals are good conductors of heat and electricity

Metals are good conductors due to presence of free electrons

They act as carrier to conduct heat or electricity.

So

Aluminum spoon will heat up as it is of metal

Iron spoon will heat up as it is of metal

Silver spoon will also heat up as it is of metal

Wood is a bad conductor of heat. It is an insulator

Wood has air space or pockets in its structure which makes it a bad conductor (it cannot conduct heat)

So a wooden spoon will be stay coolest as it is an insulator

Answer:

A silver spoon

Explanation:

because it is an insulator.

COLLEGE

how many seconds are there in 2500 years? (assume 1 year=365 days) express your answer using three significant figures

Answers

The answer is:
 7.889 x 10^10 seconds
The question gives us a conversion factor but we need more:

1 year= 365 days
1 day= 24 hours
1 hour= 60 min
1 min= 60 seconds




HIGH SCHOOL

What is the formula mass of copper (ii) sulfate to the hundredth amu?

Answers

Copper II Sulfate- Cu 2+ and a sulfate SO4 2- add together nicely to make CuSO4.
MIDDLE SCHOOL

Would tennessine have properties similar to sulfur, chlorine, or hydrogen

Answers

Answer:

IDK sorry

Explanation:

MIDDLE SCHOOL

Which of the following is an example of homeostasis? (2 points) Humans inhale when they need oxygen. Humans choose their friends. Humans wear pajamas to bed. Students are quiet in the library.

Answers

I think it’s humans inhale oxygen because that would keep the body stable which is what homeostasis is
MIDDLE SCHOOL

What does ethylene glycol do to the solution in a vehicle’s radiator? It raises the boiling point and lowers the freezing point. It lowers the boiling point and lowers the freezing point. It lowers the boiling point and raises the freezing point. It raises the boiling point and raises the freezing point.

Answers

Answer:

It raises the boiling point and lowers the freezing point.

Explanation:

It is used as antifreeze in the cooling circuits of internal combustion engines, that is, it is used to reduce the melting point of the solution.

By adding ethylene glycol I'm not only bringing the melting point to -13°C, but the boiling point of ethylene glycol is 197°C.

since these substances not only lower the freezing point but also increase the boiling point, they are also called a colligative agent

Answer:

The correct option is A) It raises the boiling point and lowers the freezing point.

Explanation:

Consider the provided information.

Ethylene glycol is often used for convective heat transfer.

The freezing point of pure ethylene glycol is about −12° C and boils at 198° C.

Due to the higher boiling point and antifreeze properties, it is used in a vehicle’s radiator.

Therefore, the correct option is A) It raises the boiling point and lowers the freezing point.

HIGH SCHOOL

40 g of calcium reacts with 71 g of chlorine to produce _____ g of calcium chloride

Answers

Answer: 111 g

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number of particles.

To calculate the moles, we use the equation:

1 moles of calcium react with 1 mole of chlorine to give 1 mole of calcium chloride.

Mass of calcium chloride =

Thus 111 g of calcium chloride is produced.

The answer is 111g of calcium chloride
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