Atomic structure, spectra and electron configurations

Question 1

what are atoms made from?

Answer 1

protons, neutrons and electrons

Question 2

give the characteristics of an electron

Answer 2

• electrons have a -1 charge
• they wizz around the nucleus in shells, these shells take up most of the volume of the atom

Question 3

give the characteristics of the nucleus

Answer 3

• most of the mass of the atom is concentrated in the nucleus
• the diameter of the nucleus is rather titchy when compared to the whole atom
• the nucleus is where you find the protons and neutrons

Question 4

whats the relative charge and mass of a proton?

Answer 4

charge: +1
mass: 1

Question 5

whats the relative charge and mass of a neutron?

Answer 5

charge: 0
mass: 1

Question 6

whats the relative charge and mass of an electron?

Answer 6

charges: -1
mass: 1/2000 (negligible)

Question 7

what do ions have different numbers of?

Answer 7

ions have different numbers of protons and electrons
- negative ions have more electrons than protons
- positive ions have fewer electrons than protons

Question 8

what are isotopes?

Answer 8

isotopes are atoms of the same element with different numbers of neutrons

Question 9

describe the nuclear model and how Rutherford proved this?

Answer 9

• a tiny, positively charged nucleus at the centre, surrounded by a cloud of negative electrons. most of the atom is empty space
• Rutherford fired alpha particles at a thin sheet of gold, the expectation was that most would be very slightly deflected but in fact almost all passed directly through and a very small number were deflected. this proved the plum pudding model incorrect and made the nuclear model.

Question 10

describe the plum pudding model

Answer 10

a positively charged sphere with negative electrons embedded in it

Question 11

describe the bohr model

Answer 11

• electrons exist in fixed orbits, or shells and not anywhere in between.
• each shell has a fixed energy
• when an electron moves between shells electromagnetic radiation is emitted or absorbed
• because the energy of the shells is fixed, the radiation will have a fixed frequency

Question 12

what particle did J J Thompson discover?

Answer 12

the electron

Question 13

what is relative atomic mass?

Answer 13

relative atomic mass is the mean weighted mass of an atom of an element compared with the 1/12th the mass of an atom of carbon-12

Question 14

what is relative molecular mass?

Answer 14

relative molecular mass is the mean weighted mass of a molecule compared with 1/12th the mass of an atom of carbon-12

Question 15

what is relative formula mass?

Answer 15

relative atomic mass is the sum of the mean weighted masses of all atoms in the formula of a compound compared with 1/12th the mass of an atom of carbon-12

Question 16

what is a mole?

Answer 16

a mole is the amount of substance containing as many particles as there are atoms in 12g of carbon-12

Question 17

what is an ionic equation?

Answer 17

an ionic equation is an equation in which only the non-spectating ions are shown

Question 18

how is percentage yield calculated?

Answer 18

= (actual yield/expected yield) x 100

Question 19

how is percentage composition by mass calculated?

Answer 19

= (mass of desired substance/mass of mixture) x 100

Question 20

how is a standard solution prepared from a concentrated solution?

Answer 20

• a certain volume of the concentrated solution is added to a volumetric flask in order to get the desired final volume
• distilled water is added to the volumetric flask up to the line on its neck

Question 21

how do you calculate the mass spectrometry of an element?

Answer 21

(%abundance x mass number) + same for all other isotopes / 100

Question 22

describe empirical and molecular formulas?

Answer 22

empirical: the simplest ratio of all the elements present in the simplest formula
molecular: the actual number of each type of atom present in one molecule of a compound

Question 23

define atom?

Answer 23

smallest piece of an element, contains protons and neutrons and is overall neutral

Question 24

what is a group and a period on the periodic table?

Answer 24

Group: a vertical column in the periodic table, same number of electrons in outer shell
Period: a horizontal row of elements in the periodic table, all with the same number of electron shells