Notice in the picture of sedimentary rocks, there is one layer on top of the other. The oldest rocks are on the bottom of the pi
le and the youngest or most recent rocks are on the top of the pile. This is known as the law or principle of
A) superposition.
B) horizontality.
C) uniformatarianism.
D) cross cutting relationships.
A) superposition.
B) horizontality.
C) uniformatarianism.
D) cross cutting relationships.
1 answer:
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The Lewis acids are electron pair acceptors due to the availability of vacant orbitals they accept electrons from the donor compounds.
is a Lewis acid due to the unfilled valence shell on carbon atom (possessing positive charge) it accepts electron readily.
is not a Lewis acid due to the presence of negative charge which represents that there are electrons available for donation.
is not a Lewis acid due to the presence of lone pair on nitrogen which is easily donated to the acceptors.
is a Lewis acid due to the availability of vacant p-orbital on boron atom.
Hence, and
are Lewis acids.
Answer:
<em>Protons: </em>
- Positively charged particle
- The number of these is the atomic number
- All atoms of a given element have the same number of these
<em>Neutrons: </em>
- Neutral particles
- Isotopes of a given element differ in the number of these
- The mass number is the number of these added to the number of protons
Explanation:
Protons (<em>positively charged</em>), neutrons (<em>neutral</em>) and electrons (negatively charged) are smaller than an atom and they are the main subatomic particles. The nucleus of an atom is composed of protons and neutrons, and the electrons are in the periphery at unknown pathways.
The <em>Atomic number</em> (Z) indicates the number of protons () in the nucleus. Every atom of an element have the <em>same atomic number</em>, thus the <em>same number of protons</em>.
The <em>mass number </em>(A) is the sum of the <em>number of protons</em> () <em>and neutrons</em> (N) that are present in the nucleus: <em>A= Z + N</em>
<em>Isotopes</em> are atoms of the <em>same element </em>which nucleus have the <em>same atomic number</em> (Z), and <em>different mass number (A)</em>, it means the <em>same number of protons</em> () and a <em>different number of neutrons</em> (N). For example, the oxygen in its natural state is a mixture of isotopes:
99.8% atoms with A= 16, Z=8, and N=8
0.037% atoms with A=17, Z=8, and N=9
0.204% atoms with A=18, Z=8, and N=10