Atomic Structure

Question 1

Electron relative mass

Answer 1

1/1840

Question 2

Nucleus

Answer 2

• carries virtually all of the mass of the atom

* positively charged

Question 3

The chemical nature of an atom is determined by…

Answer 3

The number of electron it has, and their arrangement

Question 4

Relative atomic mass

Answer 4

The average mass of one atom compared to 1/12 that of the mass of one atom of carbon-12

Question 5

Relative isotopic mass

Answer 5

The mass of one atom of an isotope compared to 1/12 of the mass of one atom of carbon-12

Question 6

Relative molecular mass

Answer 6

The average mass of a molecule compared to 1/12 of the mass of one atom of carbon-12

Question 7

Relative formula mass

Answer 7

• the same as relative molecular mass, but for ionic compounds (as these are not molecules and giant covalent substances - the size of the molecule varies - it cannot have a precise molecular mass)
• used for compounds with giant structures

Question 8

First ionisation energy

Answer 8

The energy required to remove one electron from each atom in one mole of gaseous atoms to produce one mole of gaseous ions with a 1+ charge

Question 9

Equation for first ionisation energy

Answer 9

X(g) -> X+(g) -> e-

Question 10

The first ionisation energy size provides information about…

Answer 10

… the force of attraction between the nucleus and the outer electrons

Question 11

The attraction of an electron to the nucleus depends upon

Answer 11

• the nuclear charge
• the distance from the nucleus (greater = less attraction)
• shielding (more inner electrons = less attraction)

Question 12

Nuclear charge

Answer 12

• the amount of protons relative to the amount of electrons

* the higher the charge, the greater the attraction

Question 13

Trend of first ionisation energies across a period

Answer 13

• increase
• electrons are added to the same electron shell (same distance, shielding)
• nuclear charge increases; attraction to nucleus increases
• therefore more energy is needed to remove the electron

Question 14

Trend across the periodic table for first ionisation energy

Answer 14

• group 1 has the lowest

* noble gases have the highest

Question 15

Trend for first ionisation energy across a group

Answer 15

• decrease

* distance and shielding increase

Question 16

Second ionisation energy

Answer 16

The energy required to remove one electron from each 1+ ion in one mole of gaseous ions to produce one mole of 2+ gaseous ions

Question 17

Ionisation energy

Answer 17

The energy required to remove the readily available electron from an atom, by overcoming the attraction to the nucleus

Question 18

General principles of first ionisation energy

Answer 18

• as nuclear charge increases, there is a stronger attraction, so ionisation energy increases
• as distance increases, attraction falls very rapidly - ionisation energy decreases
• shielding - inner shells repel outer electrons away from the nucleus

Question 19

Spin-pairing

Answer 19

Causes repulsion; offsets attraction to the nucleus; paired e-s are removed more easily

Question 20

Successive ionisions énergies

Answer 20

• give us important information about the electronic structure of an element
• determined which group an element is in

Question 21

Trend for successive ionisation energies

Answer 21

• the second ionisation energy of an element is always greater than the first
• after each ionisation, nuclear charge increases
• the next electron must be removed from a greater attraction

Question 22

E.g. successive ionisation energies for potassium

Answer 22

• first electron is removed from the outer-shell
• second electron has to be removed from an inner-shell; requires more energy
• the tenth electron has to be removed from the next inner shell

Question 23

If there is a large jump in successive ionisation energy

Answer 23

You have moved inwards a cell- all previous electrons were in the outer shell

Question 24

Electronic structure

Answer 24

Determines an atom’s chemical and physical properties

Question 25

Aufbau principle

Answer 25

The lowest energy sub-levels are occupied first

Question 26

Shell 1

Answer 26

* s subshell | * 2 electrons

Question 27

Shell 2

Answer 27

* s and p subshells | * 8 electrons

Question 28

Shell 3

Answer 28

* s, p and d sub-shells * 18 electrons * can expand the octet

Question 29

Shell 4

Answer 29

* s, p, d and f subshells | * 32 electrons

Question 30

The higher the energy of the shell...

Answer 30

... the more subshells it contains

Question 31

2n^2

Answer 31

Gives the number of electrons in any shell Where n is the shell number

Question 32

Orbitals

Answer 32

An area occupied by an electron wave

Question 33

S orbitals are

Answer 33

Spherical

Question 34

Electrons in the first shell have the ...

Answer 34

... same energy value, but opposite spin values

Question 35

Electrons in the p subshell

Answer 35

* are of a higher energy level than those at the s | * found in 3 different regions of the atom: x, y and z

Question 36

The 4s subshell fills up...

Answer 36

... before the 3d subshell Because an exactly half-full/full d sub-shell is particularly stable

Question 37

Hund’s rule

Answer 37

Electron orbitals are filled such that once an electron has entered an orbital of a p or d subshell, the orbital will not take on another electron until all other orbitals of the same energy level also have one electron

Question 38

s-block element

Answer 38

An element in which the last electron is in the s orbital

Question 39

Similar properties are portrayed by...

Answer 39

... elements in the same group; elements with the same number of electrons and electrons in the same type of sub-shell

Question 40

Copper and chromium

Answer 40

* exceptions to the Aufbau principle * an electron from the 4s subshell goes to the 3d subshell to give chromium a half-full d subshell and copper a full subshell Cr: 1s^22s^22p^63s^23p^64s^13d^5 Cu: 1s^22s^22p^63s^23p^64s^13d^10

Question 41

Noble gases

Answer 41

Have shells which are completely full

Question 42

[Ar]

Answer 42

* has the same electron configuration as argon | * used because it is a noble gas

Question 43

Group 4 elements

Answer 43

* tend to form giant covalent structures * elements towards the bottom of the group are metallic * Pb and Sn are metallic because they are large; electrons are further from the nucleus and there is more shielding; e-s are lost more easily

Question 44

Groups 5,6 and 7

Answer 44

* generally have simple covalent structures | * bottom of the groups become more metallic

Question 45

Group 8

Answer 45

* noble gases * have complete electron shells * monoatomic

Question 46

Moving horizontally...

Answer 46

... electron control increases as non-metallic character increases

Question 47

Moving downwards...

Answer 47

... electron control decreases due to larger atoms; electrons are further from the nucleus with greater shielding; metallic character increases

Question 48

Transition metals

Answer 48

A d-block element that forms one or more stable ions with incompletely filled d orbitals

Question 49

Melting temperatures across a period

Answer 49

Rise until group 4, then decrease

Question 50

Metals

Answer 50

* strong forces of attraction between cations and delocalised electrons * increases across a period because charge increases (charge density increases) * no of delocalised electrons increases; attraction of metallic bonding increases

Question 51

Giant molecules

Answer 51

* strong forces of attraction between nuclei and shared pair of electrons * melting temperature is at peak because vast amounts of strong covalent bonds must be broken

Question 52

Simple molecules

Answer 52

* covalent bonds gold atoms strongly in the molecule, but there are weak intermolecular forces * melting temperatures are low because intermolecular forces are weak and roughly relative to the site of the molecules

Question 53

Noble gases have the lowest melting temperatures because...

Answer 53

... they are monatomic

Question 54

Phosphate

Answer 54

(PO4)3-

Question 55

Soluble:

Answer 55

* Na+, K+, NH4+, NO3- * Cl- except Ag+ and Pb2+ * (SO4)2- except Ca2+, Ba2+ and Pb2+

Question 56

Insoluble:

Answer 56

* carbonate * oxide * hydroxide except Ca2+