1. Decreases by 4. (B)
2. The atomic number changes. (B)
3. 56/26 Fe. (C)
4. Potassium-40;t1/2=25 days. (B)
5. Takes place in the upper atmosphere. (A)
Answer:
The missing information or their role in the discovery of the cell is as follows:
Robert Hooke: He was the first scientist to called cells to tiny box-like cavities he saw in cork and illustrated as cells.
A. Leeuwenhoek: he was a microscopist and microbiologist who used microscopes and observed many other living cells. He called animalcules to these single-cell living organisms later used to prove that cells are the fundamental unit of life.
Schwann and Schleiden: They presented the theory that suggested that the cells are basic building blocks of all living things.
Virchow: He observed that the cell dividing and come from pre-existing cells.
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>
- 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
Answer:
The answer is SiO2
Explanation:
Silocon dioxide is written without a 1 after the silocon and with a 2 after the oxygen.