help plssssssssssssssss??

Explanation:

Atoms are at their most stable when their outermost energy level is either empty of electrons or filled with electrons. Sodium atoms have 11 electrons. Two of these are in the lowest energy level, eight are in the second energy level and then one electron is in the third energy level.

Any atom is most stable when it’s outermost energy level contains eight electrons.

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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Answer:1, 2, and 4

Explanation:

covalent bonds are not ionic.  the elements SHARE electrons

Which of the following are properties of compounds formed by covalent bonding (Select all that apply)  

1. When you dissolve an covalent compound in water, the solution does not conduct electricity.

2. Covalent compounds often have lower melting points than ionic compounds.

3. When you dissolve an covalent compound in water, the solution conducts electricity.

4. Covalent compounds form when combining two or more nonmetal atoms.

5. Covalent compounds form when combining a two metal atoms.

6. Covalent compounds form when combining a metal atom with a nonmetal atom.

The properties of covalent compounds are option 2, 3 and 4. Covalent bonds are weaker than ionic bonds.

Covalent bonds are formed by sharing electrons between two atoms. Non metals with comparable electronegativities forms covalent bonds. They are weaker than ionic bond. Thus have lower melting point.

Melting point depends on the bond strength that's why covalent compounds have lower melting point compared with ionic bonds.

Polar covalent bonds can conduct electricity when dissolved in water because of the presence of free electrons. Thus option 3 is correct.

Hence, the properties in option 2, 3 and 4 are correct for covalent compounds.

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Answer:

Copper = Cu

Gold = Ag

Iron = Fe

Potassium = K

Answer:

Freezing and condensation

Explanation:

Because they are exothermic, they release energy

Wavelength = Speed of Light ÷ Frequency

                     = (2.99 × 10⁸ m/s) ÷ ( 2.45 × 10⁹ /s)

                     = 1.22 × 10⁻¹ m

The wavelength of a light of frequency   2.45 × 10⁹ /s is 1.22 × 10⁻¹ m.

Notes:

Hz ≡ /s

Answer:

Explanation:

1. Virus's are hard to detect because of their simple construction.

2. Some mutate very easily.

3. It is hard to isolate the virus and kill it without doing damage to the host.

Americans breathe less pollution and face lower risks of premature death and other serious health effects. Environmental damage from air pollution is reduced. The value of Clean Air Act health benefits far exceeds the costs of reducing pollution. ... New plants and factories install modern pollution control technology.

Answer:

Sorry pal! Didn't understand your language.  

:(

Explanation:

laboratory safety rules:

~Avoid wye contact with all chemics

~ Avoid skin contact with all chemicals

~Always wear safety glasses

~Don't eat in the lab

~Don't drink anything in the lab

~Avoid wearing jewellery

~Don't taste or sniff any chemicals

~Kn0w emergency exit routes

~Never leave containers of chemicals open

~Avoid distracting anyone else working in the lab

Hope this helped you- have a good day bro cya)

Answer:It’s cyclone movement

Explanation:

Answer:

protons and neutrons

Explanation:

Neutrons and protons are the particles that are found in the nucleus of an atom.

Protons and neutrons are subatomic particles. They are present in the nucleus of an atom and constitute most of the mass of the atom. There are three kinds of subatomic particles that are present in an atom.

These are -

Since most of the mass of the atom, in the form of protons and neutrons, is present in the nucleus, the mass number is denoted as the sum of the number of protons and neutrons. Protons and neutrons together are sometimes also called nucleons.

Therefore, neutrons and protons are present in the nucleus of an atom.

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Answer:

the "goldilocks zone" is the habitable zone around a star where it's not too hot and not too cold, so liquid water and life can exist on the planets in this zone.

Explanation:

The distance Earth orbits the Sun is just right for water to remain a liquid and for life to not be frozen or fried. This distance from the Sun is called the habitable zone, or the Goldilocks zone.

the correct one is D

Answer:

a molecule is a group of atoms/elements bonded together

Answer:

First one answer is physical and other remaning chemical

Answer:

Hydrogen is a colorless, tasteless, and odorless gas.  

physical

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Hydrogen is very combustible in the presence of oxygen.  

chemical

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Hydrogen is very reactive with most elements.  

chemical

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Hydrogen is the least dense of all elements.  

physical

Answer:

Option C

Explanation:

Its totally chemical change

Answer:

What are 3 physical properties of nitrogen?

Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.09 percent of Earth's atmosphere by volume.

What are 2 chemical properties of nitrogen?

Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.09 percent of Earth's atmosphere by volume. Nitrogen gas is an industrial gas produced by the fractional distillation of liquid air or by mechanical means using gaseous air.

Answer:

it is placed over a bunsen burner to heat up and remove all bacteria

Explanation:

Answer:

(n, l, m sub l, m sub s)

N: principle quantum number (1,2,3,4,etc)

l: angular momentum quantum number, the shape (l has to be at least 1 less than n, but can be 0 depending on n)

M sub l: magnetic quantum number (l determines this number)

M sub s: spin quantum number (can only ever be 1/2 or -1/2)

Explanation:

The principle, azimuthal, magnetic, and spin quantum numbers specify the principle shell, the shape of the orbital, the number of orbitals, and electron spin respectively.

The set of numbers that describes the position and energy of the electron are called quantum numbers. Four quantum numbers are principal, azimuthal, magnetic, and spin quantum numbers.

Principal quantum numbers (n) designate the principal electron shell of the atom and the most probable distance between the nucleus and the electrons. A larger value of the principal quantum number indicates a large distance between the electron and the nucleus.

The azimuthal quantum number (l) describes the shape of an orbital in which an electron is present. Its value is equal to the total number of angular nodes in that orbital.

The magnetic quantum number describes the total number of orbitals in a subshell and the orientation of these orbitals.  The value of the spin quantum number (s) offers the direction in which the electron is spinning and it has only two possible values +½ and -½.

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Answer:

3.39e+20

Explanation:

Density = mass ÷ volume  

           = 217.0 g ÷ 24.3 cm³  

           = 8.93 g/cm³

∴ the unknown sample of mass 217.0 grams and volume of 24.3 cm³ has a density of 8.93 g/cm³.

Answer:

(Hope this helps can I pls have brainlist (crown)☺️)

Explanation:

Dalton turned Democritus' views on atoms into a scientific theory by employing experimental methods. Atoms can join or detach during chemical processes, but they never transform into a different atom.

Dalton was an excellent polymath, a natural philosopher, and a real scientist. His thorough investigations prompted him to suggest an early atomic theory for which exceptions would be difficult to uncover today:

Dalton offered the following:

Atoms are microscopic particles that make up elements. Atoms of the same element have the same size and mass; however, atoms of other elements have varying sizes and masses when compared to atoms of other elements. Subdivision, creation, and destruction of atoms are all impossible.

All of these ideas were developed after a great deal of testing. Other researchers may replicate his work, and new findings could be included into this atomic idea.

Democritus, on the other hand, was a 5th-century BC Greek philosopher. He conducted no experimental work as far as we know, and none of his publications have survived. He postulated that matter was made up of a single indivisible element known as an atom; the word atom originates from the Greek word oos, which meaning "uncuttable" or "indivisible." So the name atom might be a homage to Democritus.

Answer:

c. chlorine, with an outer electron shell filled with 7 of a possible 8 electrons

Explanation:

Hope this helps!

The structure in the option A has 7 electrons in the outer shell of its electronic configuration , is unstable and so is most likely to form bond with another atom.

Electrons are arranged in various shells around the nucleus , this arrangement is called electronic structure or configuration.

Each shell can occupy certain fixed number of electrons.

Beside Option A , all the other configurations show stable structures as the last shell has eight electrons and are stable according to the octet rule.

The structure in the option A has 7 electrons in the shell and so is most likely to form bond with another atom.

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Answer:

Explanation:

a. NaCl+ AgNO3-----> NaNO3+ AgCl

b. Số mol của NaCl= 0,2*0,5= 0,1 (mol)

------> Số mol của kết tủa AgCl tạo thành= 0,1 mol (dựa vào phương trình hóa học)

-----> Khối lượng của kết tủa AgCl tạo thành= 0,1*143,5=14,35(g)

c. Số mol của AgNO3= số mol của NaCl= 0,1 (mol)

------> Nồng độ mol của dd AgNO3 đã tham gia phản ứng= [tex]\frac{0,1}{0,4}[/tex]=0,25(M)

Answer:

b

Explanation:

Answer:

 A FLUORINE

Explanation:

Explanation:

Option A, Fluorine is the correct answer, because it has 9 electrons in its shells.

hope this helps you.

Answer:

i believe it is c

evaporation

Explanation:

Hope it's the correct one if not very sorry.

Answer: Luster: Metals are shiny when cut, scratched, or polished.

Malleability: Metals are strong but malleable, which means that they can be easily bent or shaped.

Conductivity: Metals are excellent conductors of electricity and heat.

Explanation: Hope this helped!