01 - atomic structure

Question 1

what is an element?

Answer 1

a substance containing only one type of atom, where all the atoms have the same proton number

Question 2

what is an atom?

Answer 2

• the smallest part of an element that takes part in chemical change
• usually has a nucleus with protons and neutrons surrounded by electrons outside (¹1H isotope has not neutrons)
• H atom diameter ≈ 10^-10
• H atom mass = 1.67* 10^-27

Question 3

what is a proton?

Answer 3

• a type of nucleon
• a positively charged particle in the nuclues of an atom
• relative mass = 1
• relative charge = +1
• symbol = p

Question 4

what is a neutron?

Answer 4

• a type of nucleon
• uncharged particle in the nucleus of an atom
• relative mass = 1
• relative charge = 0
• symbol = n

Question 5

what is a nucleus?

Answer 5

• part of an atom where all the mass is concentrated
• a tiny region at the atom center
• made up of particles called nucleons (protons and neutrons and the two types)

Question 6

what is an electron?

Answer 6

• found in orbitals outaide of the nucleus
• negatively charged particle with negligible mass
• actual charge on one electron = [-1.602 * 10^-19 C]
• relative mass = 1/1836
• relative charge = - 1
• symbol = e

Question 7

what is an orbital?

Answer 7

• regions of space containing electrons

Question 8

what is an energy level/quantum shell?

Answer 8

• the distances from nucleus corresponding to electron energy
• more distance = more energy
• split into sublevels called : s, p, d, f
• symbol : n, when n=1 is closest to the nucleus

n1 = 2 electrons max
n2 = 8 electrons max
n3 = 18 electrons max

Question 9

what is the atomic/proton number?

Answer 9

• number of protons in the nucleus of the atom
• number of electrons
• symbol = Z

Question 10

what is the mass/nucleon number?

Answer 10

• the number of protons + neutrons in an atom
• symbol = A

Question 11

what are isotopes?

Answer 11

• atoms of the same element with same number of protons but different numbers of neutrons
• atoms of the same element with different mass numbers
• can be radioactive (called radio isotopes) or non-radioactive
• radioisotope uses : leak check in oil or gas pipelines, paper thickness, cancer treatment medicine, thyroid gland activity in the throat

Question 12

what are ions?

Answer 12

• charged particles formed from the loss or gain of electrons from an atom or group of covalently bonded atoms
• electron gain = - ion
• electron loss = + ion

Question 13

what is a neutral atom?

Answer 13

• where number of protons = number of electrons