What determines the number of valence electrons?
For neutral atoms, the number of valence electrons is equal to the atom’s main group number. The main group number for an element can be found from its column on the periodic table. For example, carbon is in group 4 and has 4 valence electrons. Oxygen is in group 6 and has 6 valence electrons.
How does the number of valence electrons change?
1 Answer. The number of valence electrons goes up by one each time you move another column (group) to the right.
Which element has the greatest number of valence electrons?
oxygen
Is the number of valence electrons same for all these elements?
Within each column, or group, of the table, all the elements have the same number of valence electrons. This explains why all the elements in the same group have very similar chemical properties. For elements in groups 1–2 and 13–18, the number of valence electrons is easy to tell directly from the periodic table.
What group has two valence electrons?
The number of valence electrons
| Periodic table group | Valence Electrons |
|---|---|
| Group 2 (II) (alkaline earth metals) | 2 |
| Groups 3-12 (transition metals) | 2* (The 4s shell is complete and cannot hold any more electrons) |
| Group 13 (III) (boron group) | 3 |
| Group 14 (IV) (carbon group) | 4 |
How many valence electrons does an atom of oxygen have?
six valence electrons
Is the number of shells the same in this?
number is same as the number of shell which in gradually filled up in the elements of this period.
How do you determine the number of electron shells?
The number of electrons is equal to the atom’s atomic number, which is at the top left of the element. For example, assume you want to know how many rings are in the element neon. Neon on the periodic table has an atomic number of 10, so it has 10 electrons. Square the ring number, then multiply the result by two.
How many electrons are in the 4th Shell?
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| Shell | Subshell | Total Number of Electrons in Shell |
|---|---|---|
| 1st Shell | 1s | 2 |
| 2nd Shell | 2s, 2p | 2 + 6 = 8 |
| 3rd Shell | 3s, 3p, 3d | 2 + 6 + 10 = 18 |
| 4th Shell | 4s, 4p, 4d, 4f | 2 + 6 + 10 + 14 = 32 |
Why is 3rd shell 8 or 18?
In this sense the third shell can hold 8 electrons. In this sense the third shell can hold a total of 18 electrons. So the third shell can be considered to hold 8 or 18 electrons but in total the third shell can hold 18 electrons.
What is the 2 8 8 rule in chemistry?
There is a 2-8-8 rule for these elements. The first shell is filled with 2 electrons, the second is filled with 8 electrons, and the third is filled with 8. You can see that sodium (Na) and magnesium (Mg) have a couple of extra electrons. They, like all atoms, want to be happy.
Why does the number of electrons in the third shell suddenly change from 8 to 18?
Explain why the number of electrons in the third shell suddenly changes from 8 to 18 between the element calcium, Ca, and Gallium, Ga? Because there are 10 euments between Ca and Ga. 8.
Why are there 8 electrons in the second shell?
Because the first shell can only hold a maximum of 2 electrons, the third electron must go into the second shell. The 2s subshell holds a maximum of 2 electrons, and the 2p subshell holds a maximum of 6 electrons. This means that the second shell can hold a maximum of eight electrons (2+6=8).
Why can an atom only have 8 valence electrons?
The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds.
Why can’t atoms only have 8 valence electrons?
An atom with less than 8 electrons in its outermost shell (known as the valence shell) has room in its s or p valence subshells. When it interacts with other atoms these can act as empty slots for new electrons to fall into. If an atom gets up to 8 electrons in this way the s and p valence subshells will be full.
Which atoms Cannot have more than 8 valence electrons?
Sulfur, phosphorus, silicon, and chlorine are common examples of elements that form an expanded octet. Phosphorus pentachloride (PCl5) and sulfur hexafluoride (SF6) are examples of molecules that deviate from the octet rule by having more than 8 electrons around the central atom.
Can XE have more than 8 valence electrons?
Xe does not follow the octet rule. It actually bonds. It will hold more than 8 electrons. Xenon having valence electrons in the 4th energy level, will also have access to the 4d sublevel, thus allowing for more than 8 electrons.
Can phosphorus have more than 8 valence electrons?
Phosphorus pentachloride (PCl5) and sulfur hexafluoride (SF6) are examples of molecules that deviate from the octet rule by having more than 8 electrons around the central atom.
Why does sulfur have 12 valence electrons?
Sulfur has one more electron pair in its 3s subshell so it can undergo excitation one more time and place the electron in another empty 3d orbital. Now sulfur has 6 unpaired electrons which means it can form 6 covalent bonds to give a total of 12 electrons around its valence shell.
Can Boron have more than 3 bonds?
Boron commonly makes only three covalent bonds, resulting in only six valence electrons around the B atom. A well-known example is BF 3: The third violation to the octet rule is found in those compounds with more than eight electrons assigned to their valence shell.
Why does Beryllium only need 4 electrons?
In some compounds, the number of electrons surrounding the central atom in a stable molecule is fewer than eight. Beryllium is an alkaline earth metal and so may be expected to form ionic bonds. Since beryllium only has two valence electrons, it does not typically attain an octet through sharing of electrons.
Can boron Form 4 bonds?
The boron shares its three electrons with three fluorine atoms. The fluorine atoms follow the octet rule, but boron has only six electrons. Although atoms with less than an octet may be stable, they will usually attempt to form a fourth bond to get eight electrons. BF3 is stable, but it will form BF4- when possible.
What type of bond does boron form?
covalent bond
Why is boron an exception?
The problem with this structure is that boron has an incomplete octet; it only has six electrons around it. Hydrogen atoms can naturally only have only 2 electrons in their outermost shell (their version of an octet), and as such there are no spare electrons to form a double bond with boron.