trends and the history of the atom

Question 1

what is the atomic radius trend

Answer 1

the measure of the size of atoms, usually from the nucleus to the other shell

Question 2

what is the electronegativity trend

Answer 2

The ability for the atom to attract or hold onto its electrons in a chemical bond. the closer it is to fluorine the higher the electronegativity.

Question 3

what is the ionisation energy trend

Answer 3

the energy required to remove one mole of the electron from 1 mole of atoms

Question 4

what is the atomic radius trend down a group

Answer 4

due to the atom gaining a valence shell, the radius becomes larger due to the gain of shell

Question 5

what is the atomic radius across a group

Answer 5

due to the electrostatic attraction between the electrons and the positive nucleus being stronger. the valence electron gets pulled in closer to the nucleus causing the atomic radius to decrease

Question 6

what is the electronegativity down a group

Answer 6

decreases down a group since the valence electrons are further from the nucleus

Question 7

what is the electronegativity across a period

Answer 7

due to the electrostatic attraction being stronger between the nucleus and valence electrons, the electrons become closer to the nucleus causing the electronegativity to increase due to the electrons being more tightly attracted to an atom

Question 8

what is the ionisation down a group

Answer 8

due to the valence shells being further away, the electrostatic attraction isn’t as strong between the nucleus and the electrons. this causes the amount of energy to remove an electron decrease

Question 9

what is the ionisation across a group

Answer 9

due to the valence shells being closer to the nucleus due to the strong electrostatic attraction. the amount of energy needed to lose an electron is increased

Question 10

what are the two main categories of matter

Answer 10

pure substances and mixtures

Question 11

what are homogeneous mixtures

Answer 11

a mixture which has a uniform composition and properties throughout

Question 12

what are heterogeneous mixtures

Answer 12

a mixture that doesn’t have uniform composition and properties throughout

Question 13

which five scientists were involved in developing the structure of the atom

Answer 13

John Dalton, JJ Thompson, Ernest Rutherford, Bohr, Chadwick

Question 14

what involvement did john dalton have with the structure of the atom

Answer 14

used carbon as an example and stated that all atoms in carbon are the same but are different form that of sulphur

Question 15

what involvement did JJ Thompson have with the structure of the atom

Answer 15

based on his experiments came up with the ‘plum pudding model’ where the atom was a sphere of positive charge and negative electrons were dispersed inside it.

Question 16

what involvement did Ernest rutherford have with the structure of the atom

Answer 16

through his gold foil experiment, he designed a model with the small but dense positive centre with electrons surrounding and lots of empty space

Question 17

what involvement did Bohr have with the structure of the atom

Answer 17

electrons have energy levels

Question 18

what involvement did Chadwick have with the structure of the atom

Answer 18

he discovered the neutrons in the atom

Question 19

how are al atoms held together

Answer 19

an electrostatic attraction between the nucleus and the electrons

Question 20

what are isotopes

Answer 20

atoms of an element with the same number of protons but different numbers of neutrons and are represented in the form A X (IUPAC) or X-A. they have the same electron configuration and similar chemical properties but have different physical properties

Question 21

what is the relative mass of an atom

Answer 21

the ratio of the average mass of the atom to 1/12 the mass of an atom of 12C; relative atomic masses of the elements are calculated from their isotopic composition

Question 22

what are allotropes

Answer 22

a different form of the same element. for example, diamond and graphite are allotropes of carbon. these all have different chemical properties

Question 23

what are fullerenes

Answer 23

a newly formed allotrope of carbon that was found by harold Kroto. the molecule known as buckminsterfullerene was the first C60 fullerene to be discovered in 1985. it consists of 60 carbon atoms covalently bonded into a cage structure consisting of 12 pentagons and 20 hexagons, resembling a soccer shape

Question 24

what is electron affinity

Answer 24

when an electron is added to an atom to give a negative ion