Answer: The mass number of an oxygen isotope that has nine neutrons is 17 and isotope is called as Oxygen-17.
Explanation:
Atomic number is defined as the number of protons or number of electrons that are present in an atom.
For a neutral atom:
Atomic number = Number of electrons = Number of proton
Atomic number= Number of protons = 8
Mass number is defined as the sum of number of protons and neutrons that are present in an atom.
Mass number = Number of protons + Number of neutrons
Given: Number of neutrons = 9
Thus mass number = Number of protons + Number of neutrons = 8 + 9 = 17.
Isotopes are elements which have same atomic number but different mass number.
Thus the mass number of an oxygen isotope that has nine neutrons is 17 and isotope is called as Oxygen-17.
Subatomic particles include electrons, the negatively charged, almost massless particles that nevertheless account for most of the size of the atom, and they include the heavier building blocks of the small but very dense nucleus of the atom, the positively charged protons and the electrically neutral neutrons.
And I don't see any of the particles. so I can only answer the first one.
The half life of a radio-isotope is the amount of time required for half of the isotope to decay into a new element or sister isotope. One half life results in a 50% loss of radioisotope, and two half lives results in a 75% loss. For three-fourths of the nuclei to decay, two half-lives must pass.
Alkali metals have only one electron in their outermost energy levels , so (they can loose one electron to) they form a mono positive ion only . That's why alkali metal do not from dispositive ions .
Hope that helps:)
14) gas to liquid to solid
15)chlorine displaces bromine from potassium bromide
16) non-metals
6)vertical
7)similar properties
8)there are patterns
10)decrease
11)very reactive
12) hydrogen
18)lower density than air
19)better insulator
20)metalloids
