However, there are three general exceptions to the octet rule: Molecules, such as NO, with an odd number of electrons; Molecules in which one or more atoms possess more than eight electrons, such as SF6; and. Molecules such as BCl3, in which one or more atoms possess less than eight electrons.
Q. Why does helium only need 2 valence electrons?
Explanation: Helium is located in period 1, group 18 of the Periodic Table and has an atomic number equal to 2. As a result, neutral helium will only have 2 electrons surrounding its nucleus. Valence electrons are the electrons located in an atom’s outermost shell.
Table of Contents
- Q. Why does helium only need 2 valence electrons?
- Q. Why is there no octet rule for hydrogen?
- Q. Why does BCl3 violate the octet rule?
- Q. Why does bf3 violate the octet rule?
- Q. What is the octave rule?
- Q. What is the rule for going down an octave?
- Q. Why is the octet rule true?
- Q. Which is the last element to follow the law of octaves?
- Q. Who gave the law of triads?
- Q. Why is it called law of octaves?
- Q. Is Fe Co Ni are dobereiner Triad?
- Q. Is P as SB are dobereiner triads?
- Q. Which of the following is dobereiner traid?
- Q. What are the two sets of Triads dobereiner observed?
- Q. Why were dobereiner’s ideas not accepted?
- Q. What problem did Cannizzaro solve?
- Q. Is s se te a triad?
Q. Why is there no octet rule for hydrogen?
octet rule: Atoms lose, gain, or share electrons in order to have a full valence shell of eight electrons. Hydrogen is an exception because it can hold a maximum of two electrons in its valence level.
Q. Why does BCl3 violate the octet rule?
The central boron atom in boron trichloride (BCl3) has six valence electrons as shown in Figure 1.2. There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule.
Q. Why does bf3 violate the octet rule?
Electron-deficient molecules. 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.
Q. What is the octave rule?
Law of octaves, in chemistry, the generalization made by the English chemist J.A.R. Newlands in 1865 that, if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements.
Q. What is the rule for going down an octave?
The key principle behind the Rule of the Octave is that scale degrees ➀ and ➄ receive what we would call a root position triad — notated in figured bass by a 5 over a 3 (which I will typeset as 5/3) although these are typically left implied and no figures are are written.
Q. Why is the octet rule true?
Atoms will react to get in the most stable state possible. A complete octet is very stable because all orbitals will be full. This octet can be made up by own electrons and some electrons which are shared. Thus, an atom continues to form bonds until an octet of electrons is made.
Q. Which is the last element to follow the law of octaves?
thorium
Q. Who gave the law of triads?
In 1829, a German chemist, Johann Dobereiner (1780–1849), placed various groups of three elements into groups called triads.
Q. Why is it called law of octaves?
In the year 1866, an English scientist, John Newlands arranged the elements in the order of increasing atomic masses. He noticed that every eighth element exhibits similar properties as compared to the first element. He called this law as the ‘Law of Octaves’ better known as ‘Newland’s Law of Octaves’.
Q. Is Fe Co Ni are dobereiner Triad?
The elements lithium, sodium and potassium form a dobereiner’s triad. Considering the question as the atomic weight of the middle element is not the same as an average of the weight of the other two elements. Therefore, Fe, Co, Ni is not a Doberiner triad.
Q. Is P as SB are dobereiner triads?
These three elements are Phosphorus, arsenic and antimony. The atomic weight of phosphorus is 31. The atomic weight of antimony is 122. which is not close to the actual mass and hence it does not follow Dobereiner’s triad rule.
Q. Which of the following is dobereiner traid?
By 1829, Döbereiner had found other groups of three elements (hence “triads”) whose physical properties were similarly related….Döbereiner’s triads.
Triad name | Iron triad | |
---|---|---|
Elements and atomic masses | Element 1 Mass | Iron 55.8 |
Element 2 Mean of 1 and 3 Actual mass | Cobalt 57.25 58.9 | |
Element 3 Mass | Nickel 58.7 |
Q. What are the two sets of Triads dobereiner observed?
Since elements were classified into sets of three, we call the law as the law of triads. The first triad was recognized in 1817. It consisted of calcium, strontium, and barium. Other triads were found in the following years….Explanation.
Triad | Triad 2 |
---|---|
Elements | Calcium |
Symbol | Ca |
Atomic weight | 40.1 |
Average | – |
Q. Why were dobereiner’s ideas not accepted?
His ideas were rejected at the time for several reasons: Metals are grouped with non-metals, e.g. oyxgen is in the same group as iron. Not all of the elements in a group have the same properties, e.g. copper is unreactive and it is in the same group as potassium which explodes on contact with water.
Q. What problem did Cannizzaro solve?
Cannizzaro showed how the atomic weights of elements contained in volatile compounds can be deduced from the molecular weights of those compounds, and how the atomic weights of elements of whose compounds the vapour densities are unknown can be determined from a knowledge of their specific heats.
Q. Is s se te a triad?
S, Se, Te are the elements of a triad.