Answer:
Option A
Explanation:
Addition of too much of solvent will make the solution dilute due to which the crystals will not form. Hence option D is incorrect
On the other hand adding a minimum amount of boiling solvent will give a saturated solution for recrystallization. Hence, option A is incorrect
Addition of cold solvent will lower the rate of formation of crystals. Hence, both option B and C are incorrect
Answer:
The most stable conformer would be the anti-conformer when the substituent methyl groups are farthest away from each other.
Explanation:
Isomers are chemical compounds with the same molecular formula but with different molecular structures.
Conformers are a special type of isomers that produce different structures when the substituents of a Carbon-Carbon single bond (C-C) are rotated.
In 2,3 dimethyl butane, the substituent methyl groups are located around the second and third Carbon to Carbon single bond.
To achieve a stable configuration, the methyl group substituents need to be as far apart as possible (that is, in an anti-position) to minimise repulsion.
The closer the methyl groups are to each other, the more they repel each other and the more unstable the conformer becomes.
The location of the valence electron or the outermost electron is expressed in quantum numbers. There are five quantum numbers: prinicipal (n), angular momentum (l), magnetic (ms) and magnetic spin (ms) quantum numbers. This is based on Bohr's atomic model where electrons orbit around the nucleus. These electrons are in the orbitals with specific energy levels. Starting from energy level 1 that is closest to the nucleus, the energy level decreases to 2, 3, 4, 5, 6, and 7. These energy level numbers represent the principal quantum number. Within each orbital also contains subshell. From increasing to decreasing order, these subshells are the s, p, d and f subshells. These subshells represent the angular momentum quantum numer. Specifically, s=0, p=1, d=2 and f=3. Therefore, if the electron is in the orbital 5p, the quantum number would be: 5, 1. Applying these, the correct pairing would be:
2p: n=2. l=1
Answer:
A reactant is a substance that is present at the start of a chemical reaction. A product is a substance that is present at the end of a chemical reaction.
Explanation:
<span>
</span>Types of Compounds
Ionic compounds are compounds composed of ions, charged particles that form when an atom (or group of atoms, in the case of polyatomic ions) gains or loses electrons.
<span><span>A cation is a positively charged ion</span><span>An anion is a negatively charged ion.</span></span>
Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral.
Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other. Since hydrogen is a nonmetal, binary compounds containing hydrogen are also usually covalent compounds.
<span>Metal + Nonmetal —> ionic compound (usually)Metal + Polyatomic ion —> ionic compound (usually)Nonmetal + Nonmetal —> covalent compound (usually)<span>Hydrogen + Nonmetal —> covalent compound (usually)</span></span><span>
Types of Ions:</span>
<span>Main-Group Metals (Groups IA, IIA, and IIIA)</span>
Group IA, IIA, and IIIA metals tend to form cations by losing all of their outermost (valence) electrons. The charge on the cation is the same as the group number. The cation is given the same name as the neutral metal atom.
Ions of Some Main-Group Metals (Groups IA - IIIA)
<span><span>GroupElementCationIon name</span><span>IAH<span>H+</span>hydrogen ion</span><span> Li<span>Li+</span>lithium ion</span><span> Na<span>Na+</span>sodium ion</span><span> K<span>K+</span>potassium ion</span><span> Cs<span>Cs+</span>cesium ion</span><span>IIAMg<span>Mg2+</span>magnesium ion</span><span> Ca<span>Ca2+</span>calcium ion</span><span> Sr<span>Sr2+</span>strontium ion</span><span> Ba<span>Ba2+</span>barium ion</span><span>IIIAAl<span>Al3+</span>aluminum ion</span></span>
