Answer:
Different isotopes of the same element have the same number of protons in their atomic nuclei but differing numbers of neutrons. Radioisotopes are radioactive isotopes of an element. They can also be defined as atoms that contain an unstable combination of neutrons and protons, or excess energy in their nucleus.
atoms are made of 3 types of subatomic particles; electrons, protons and neutrons
atomic number is the number of protons. atomic number is characteristic for the element. In ground state atoms, the number of electrons and protons are the same.
the electronic configuration of Ca in the ground state is
Ca - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
when Ca loses its 2 valence electrons, it becomes positively charged and the electronic configuration becomes
Ca - 1s² 2s² 2p⁶ 3s² 3p⁶
number of electrons in Ca²⁺ is 18
the atom in the ground state would have the same number of electrons and protons. Therefore number of protons are 18. then the atomic number of the element is 18
the atom having an atomic number of 18 is Ar.
the answer is 1) Ar
The statement is true. The octet rule refers to the general rule of thumb wherein atoms of main-group elements tend to bond with other atoms in such a way that each atom possesses eight electrons (octet) in their valence shell. They tend to form the same electronic configuration as the noble gases. However, there are some exceptions to this rule. One of which is silane, SiH₄. A hydrogen atom only has 1 valence electron and needs another electron to complete its energy level. This is unlike other atoms, for example, carbon which has 4 valence electrons and needs to form 4 covalent bonds to fill its energy levels. Thus, 4 hydrogen atoms need only 4 more electrons. This is given by the silicon atom which has 4 valence electrons. Therefore, when a silicon atom is bonded to 4 hydrogen atoms, the resulting molecule, SiH₄, is a stable one.
Answer:
CuSO4
Explanation:
Na2S + CuSO4 → Na2SO4 + CuS
The reaction is balanced (same number of elements in each side)
To determine limiting reagent you need to know the moles you have of each.
Molar mass Na2S = 23 * 2 + 32 = 78
Molar mass CuSO4 = 63.5 + 32 + 16 * 4 = 159.5
Na2S mole = 15.5 / 78 = 0.2
CuSO4 mole = 12.1/159.5 = 0.076
*Remember mole = mass / MM
With that information now you have to divide each moles by its respective stoichiometric coefficient
Na2S stoichiometric coefficient : 1
Na2S : 0.2 / 1 = 0.2
CuSO4 stoichiometric coefficient: 1
CuSO4: 0.076 / 1 = 0.076
The smaller number between them its the limiting reagent, CuSO4
Answer:
Option A. the hydroxyl group (-OH)
Explanation:
Ethanol, CH₃CH₂OH belongs to the class of organic compound called alkanol.
They have general formula as R–OH
Where
R => is an alkyl group
OH => is the hydroxyl group
The hydroxyl group (OH) is the functional group of the alkanol (alcohol)
