Biology 1. Define and provide an example for an element, compound and a mixture.
ID: 86366 • Letter: B
Question
Biology
1. Define and provide an example for an element, compound and a mixture.
2. Describe each of the sub atomic particles (protons, neutrons and electrons).
3. Know how to calculate the number of electrons in the outer shell.
4. What is an isotope?
5. What is an ion?
6. Know the difference between the atomic number and the atomic mass (weight).
7. Explain the three types of bonding (ionic, covalent, hydrogen) with examples.
8. Define acids and bases including an example for each.
9. What is the difference between hydrolysis and dehydration synthesis?
10. Describe the role of water in hydrolysis and dehydration synthesis.
11. Describe the four types of macromolecules (proteins, carbs, lipids, nucleic acids) including an example of each.
Explanation / Answer
Answer 1:
An element is a substance which cannot be further broken down into simpler components. For example, silver cannot be broken down into anything other than gold.
When two or more elements combine together by chemical bonds, they form a compound. Such as water is a compound formed by the combination of one molecule of hydrogen and two molecules of oxygen.
Mixture is a combination of two or more pure substances such as elements that retain their individual chemical properties even when mixed. A mixture of fruits is a mixture. A mixture of inert gases is a mixture.
Answer 2:
Electrons: Electrons are subatomic particles that revolve around the nucleus in more or less circular orbits. They have a charge equivalent to 1.60217662 × 10-19 coulombs. they are the least heavy of the three subatomic particles.
Protons: These are subatomic particles within the nucleus of the atom. They have a positive charge equivalent to that of an electron. A proton is 1837 times heavier than an electron.
Neutrons: Like the protons these are subatomic particles within the nucleus of the atom. They do not possess any charge. have a positive charge equivalent to that of an electron. Neutrons are slightly heavier than the protons.
Answer 3:
According to the Bohr's model, each shell in the atom can hold only a specific number of electrons. The 1st shell can hold only up to two electrons, the 2nd shell can hold up to eight (2 + 6) electrons, the 3rd shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2). So, once you know the atomic number of the element whose electrons you wish to find in its outermost orbit, you can start distributing the electrons in the orbits as per the formula and get the number of electrons in the outermost orbits. For example, if you wish to know the electrons in the outermost orbit of nitrogen whose atomic number is 14. then we start by allocating 2 electrons in the first orbit, then 6 in the second and then remaining 4 in the last orbit. So, nitrogen has 4 electrons in its last orbit.
Answer 4:
Elements having same atomic number but different atomic mass are referred to as isotopes. The difference in atomic mass is due to the difference in the number of neutrons in the nucleus.
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