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SSSSS [86.1K]
3 years ago
6

The universe contains billions of galaxies, each containing billions of stars. True or false

Chemistry
2 answers:
Tatiana [17]3 years ago
8 0
True but no one know Exactly how many stars there are
Komok [63]3 years ago
6 0
This is true but there could be more stars and galaxies.
You might be interested in
If you knew the number of valence electrons in a nonmetal atom how would you determine the valence of the element. (Ignore hydro
SIZIF [17.4K]

Answer:

The possible valances can be determined by electron configuration and electron negativity

Good Luck even though this was asked 2 weeks ago

Explanation:

All atoms strive for stability. The optima electron configuration is the electron configuration of the VIII A family or inert gases.

Look at the electron configuration of the nonmetal and how many more electrons the nonmetal needs to achieve the stable electron configuration of the inert gases. Non metals tend to be negative in nature and gain electrons. ( They are oxidizing agents)

For example Florine atomic number 9 needs one more electron to reach a valance number of 8 electrons to equal Neon atomic number 10. Hence Flowrine has a valance of -1

Oxygen atomic number 8 needs two more electrons to reach a valance number of 8 electrons to equal Neon atomic number 10. Hence Oxygen has a valance charge of -2.

Non metals with a low electron negativity will lose electrons when reacting with another non metal that has a higher electron negativity. When the non metal forms an ion it is necessary to look at the electron structure to determine how many electrons the element can lose to gain stability.

For example Chlorine which is normally -1 like Florine when it combines with oxygen can be +1, +3, + 5 or +7. It can lose its one unpaired electron, or combinations of the unpaired electron and sets of the three pairs of electrons.

6 0
3 years ago
What are the trends for atomic size and ionization? Explain why for each trend. Tell me the direction- up or down a group and ac
Alinara [238K]

Answer:

See explanation

Explanation:

Atomic size increases down the group due to the addition of more shells.

As more shells are added and repulsion of inner electrons become more significant, atomic size increases down the group. However, across the period, atomic size decreases due to increase in effective nuclear charge without any increase in the number of shells. This causes increased attraction between the nucleus and the outermost shell thereby decreasing the size of the atom.

Ionization energy decreases down the group because the outermost electron is more shielded by inner electrons making it easier for this outermost electron to be lost. Across the period, ionization energy increases due to increase in effective nuclear charge which makes it more difficult to remove the outermost electron due to increased nuclear attraction.

5 0
3 years ago
when copper is bombarded with high energy electron x rays are emitted.Calculate the energy(in joule) associated with photons if
kakasveta [241]
The answer that i got was three
 i redid it and got some answer like 4.62 x1014<span> Hz</span>
3 0
3 years ago
What did Bohr’s model of the atom do that Rutherford’s model did not?
Dafna1 [17]

Answer:

The last option

Explanation:

The Bohr model was an attempt to explain atomic hydrogen's spectrum. This was done by establishing energy levels of separate electron orbits in the atom.Thos model was followed by the Schrödinger model.

5 0
4 years ago
Read 2 more answers
1. A chemical bond between metals and nonmetals; valence electrons are transferred ____.
Law Incorporation [45]

Answer:

1. Ionic bonding

2. Covalent bonding

3. Metallic bonding

Explanation:

Ionic bonding also referred to as electrovalent bonding is a kind of chemical bonding that involves the transfer of electrons between the valence shells of two elements with a large electronegativity difference usually a metal and a nonmetal.

For example an ionic bonding scenario might play out between a group one metal and a group seven halogen. While group one metals have one electron hindering their stability, group seven halogens need that one electron that could make them achieve this stability. It is this that causes them to come together in a way where the electron is transferred completely from the valence shell of the group 1 atom and accepted into the valence shell of the group 7 halogen.

Covalent bonding involves the sharing of electrons between atoms of comparable electronegativities. The electro negativity difference is not large enough to permit the total movement of the electrons and hence the electrons are then controlled by the nuclei of the two atoms

Between two metals, what we have is called the metallic bonding

7 0
3 years ago
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