1.1 + 1.2 Formulae and equations/Basic Ideas about Atoms Flashcards

Question

mole

Answer 1

amount of substance that has the same number of particles as there are number of atoms in C12/Avogadros number

Answer 2

the simplest whole number ratio of atoms present in a compound

Answer 3

divide by 1000

Answer 4

multiply by 1000

Answer 5

number of electrons that nned to be added or taken away to make an element neutral

Answer 6

All uncombined elements have an oxidation number of zero. E.g. in O2 gas the oxidation number = 0

Answer 7

The sum of oxidation numbers in a compound is zero. E.g. in MgO, Mg = +2, O = –2, +2 – 2 = 0

Answer 8

In an ion, the sum equals the overall charge. E.g. in NO3– the sum of oxidation numbers = –1, Nitrogen = +5, Oxygen = -2, +5 + (–2 x3) = –1

Answer 9

Group 1 metals have an oxidation number of +1; Group 2 metals have an oxidation number of +2.

Answer 10

Group 6 elements usually have an oxidation number of –2; Group 7 elements usually have an oxidation number of –1.

Answer 11

The oxidation number of oxygen is –2, except in peroxides (in H2O2 it is –1) or when combined with fluorine.

Answer 12

The oxidation number of hydrogen is +1, except in metal hydrides. For example, in NaH, hydrogen is –1 because Group 1 metals like Na always have an oxidation number of +1.

Answer 13

Oxidising agents - O Reducing agents - H then balance

Answer 14

conc (mol/dm3)

Answer 15

occurs when unstable nucleus becomes more stable via giving out energy eg electrons

Answer 16

two protons, two neutrons helium neclei

Answer 17

alpha - positive, slowmoving, weakly attracted to negative plate of electric field beta - light, fastmoving, deviation towards positive plate of electric field gamma - short wavelenth, therefore unaffected by an electric field positron - more attracted to negative plate than alpha, as lower mass

Answer 18

alpha - least penetrating, paper beta - thin layer of foil gamma - stopped thick plate of lead

Answer 19

alpha - most ionising, remove electrons from atoms, high positive charge, strongly attracts electrons beta - less ionising, collide with electrons in atoms, knock them out, ionise the atom gamma - least ionising, ionises atoms if electron absorbs energy of gamma unlikely due to short wavelength

Answer 20

anti electrons same mass but positive charge

Answer 21

when positrons and electron come in contact, they annihilate, creating gamma radiation

Answer 22

high energy EM radiation short wavelength high frequency emited after electron capture (proton rich nucleus absorbs inner electron, which combines with proton to form a neutron)

Answer 23

bottom number determines element

Answer 24

atomic mass - bigger, top atomic number - smaller, bottom

Answer 25

time takes for the mass of a radioactive substance to fall to half its original value

Answer 26

radiation absorbed by a neutral atom electron is removed atom is ionised

Answer 27

Late Effect of Ionising Radiation: DNA of a cell is damaged becomes cancerous divides uncontrollably tumors Acute Effect: Large doses of radiation can cause cell death Kill cancer cells, harmful bacteria, and other microorganisms

Answer 28

Inside the body: alpha - most ionising, most damage to living cells beta and gamma - less ionising, more likely to pass through

Answer 29

Outside the body: alpha - least penetrating, can't reach living cells under dead cells beta and gamma - more dangerous, can penetrate dead cells on surface and damage living cells beneath

Answer 30

radioactive materials injected, radiation detectors, beta or gamma used, short half-life, easily pass through body, not easily absorbed as alpha by cells

Answer 31

beam of gamma focused on tumor, kills cancer cells, radiation can damage/kill healthy cells, rotating gamma source focus on tumor, minimise exposure to healthy cells

Answer 32

eg carbon 14, long half-life carbon 14 decays by counting remaining carbon atoms

Answer 33

beta source and detector, rollers move depending on level of radiation recieved

Answer 34

measure of energy required to remove one or more electron from an atom

Answer 35

energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions

Answer 36

the energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

Answer 37

change in principle energy level electron removed from an energy level closer to the nucleus (less shielding) so more energy required eg if large jumpe between group 2 and 3 Element is in group 2

Answer 38

1. atomic radius - greater radius, e- easier to remove, outer e- feels reduced nuclear charge 2. number of protons - increase protons, increase force of attraction to nucleus 3. shielding - repulsion by electrons in shells between electron and nucleus, outershell electrons are held less tightly The screening effect or shielding effect refers to the decrease in the nucleus's force of attraction on valence electrons due to the existence of electrons in the inner shells. SO weaker force of electrostatic attraction between nucleus and outer shell electron

Answer 39

Nuclear charge refers to the total positive charge found in the nucleus of an atom the higher the nuclear charge, the higher the ionisation energy the greater the positive charge of the nucleus, the stronger the attraction for the outer electrons.

Answer 40

first IE decreases down groups increasing atomic radius, increasing shielding, reduces electrostatic attraction

Answer 41

generally increases, number of protons in nucleus increase, increases nuclear charge Each electron in an energy level is not identical

Answer 42

The 4s is filled before the 3d because it is lower in energy.

Answer 43

the 3d orbital becomes lower in energy than the 4s orbital when filled 4s electrons are removed before the 3d electrons when transition metals are ionised Copper reduced electron electron repulsion in d shell

Answer 44

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

Answer 45

increased nuclear attraction distance to nucleus is constant, shielding is constant, number of protons steadily incrasing

Answer 46

expected configuration (based on the Aufbau principle) would be: Ar 3d4 4s2 However, the actual configuration is: Ar 3d5 4s1 This is because having a half-filled 3d subshell provides extra stability due to reduced electron repulsion

Answer 47

configuration 2p6 meaning it is a noble gas with a completely filled outer shell, which is the most stable electron configuration in nature. 2p1 This lone electron is less stable because it is far from the nucleus and not part of a stable full or half-full configuration. C has a greater effective nuclear charge (ENC) than A, which means its electrons are pulled closer to the nucleus and are harder to remove. ENC increases as the number of protons increases and the outermost electrons are shielded less by inner electrons. In C, the electrons are evenly distributed in filled subshells, minimizing electron-electron repulsion. In A, the single electron in the 2 p 2p orbital experiences less stability because it is less shielded and subject to greater interactions.

Answer 48

radio waves (at the lowest frequency and longest wavelength) to gamma rays (at the highest frequency and shortest wavelength).

Answer 49

E=J h=Js f=Hz h is Planck’s constant and has a value of 6.63 × 10-34 Js. This constant is given on the AS examination data sheet. Since h is a constant, then E α f. Therefore, if the frequency increases, the energy increases.

Answer 50

c=ms-1 f=Hz wvleng=m c is the speed of light and is a constant, with a value of 3 × 10^8 ms-1. nm to m 1x10^-9 As c is a constant, when frequency increases, wavelength decreases.

Answer 51

calculate the frequency using the given wavelength use the wavelength to calculate the energy in J multiply the energy in joules by Avogadro’s number (NA, 6.02 × 1023 mol-1) to get the energy in J mol-1 divide the energy value by 1000 to convert from J mol-1 to kJ mol-1.

Answer 52

certain specific energy has been absorbed, then only a specific frequency of light is absorbed from the electromagnetic spectrum - this appears as a “missing” line or frequency in the spectrum.

Answer 53

An emission spectrum is a series of lines which correspond to particular frequencies of energy emitted by an excited species.

Answer 54

the gap between energy levels is fixed

Answer 55

in ultra violet and visable regions of the EM spectrum

Answer 56

If the excited electron falls back into the n=2 energy level (second shell), then the energy of light emitted is in the visible region of the electromagnetic spectrum and appears as coloured lines. You need to remember the origin of the first four lines in the visible emission spectrum. when drawring, n=3 to n=3 for first line in visable region

Answer 57

If the excited electron falls back into the n=1 energy level (first shell), then the energy of light emitted is in the ultraviolet part of the electromagnetic spectrum and thus can only be detected electronically, such as with a UV-Vis spectrometer.

Answer 58

The Convergence Limit -spectral lines become closer and closer as frequency of radiation increases until they converge to a limit -Within the Lyman series, the frequency of this convergence limit corresponds to the energy required to remove the electron (i.e. the ionisation energy). -The lines get closer together toward the convergence limit because the energy levels get closer together the further away they are from the nucleus.

Answer 59

Transition between n=1 level and the convergence limit, where the energy levels are so far from the nucleus that they are effectively the same energy. At this point, the electron is effectively removed from the atom and therefore corresponds to ionisation. Therefore, the transition from n=1 to n = ∞ corresponds to the atom losing the electron completely. The ionisation energy of the hydrogen atom corresponds exactly to the highest frequency line in the Lyman series of the hydrogen atom spectrum since they both refer to exactly the same process. Measuring the convergent frequency allows the ionisation energy to be calculated from E = hf.

Answer 60

convergence limit

Answer 61

ionisation energy

Answer 62

Lyman Series

Answer 63

Balmer Series

Answer 64

lower bond energy, bond can absorb lower energy photons, correspond to longer wavelentghs

Answer 65

if absorbtion within visible range will absorb specific wavelengths of visible light unabsorbed wavelengths of visible light will be transmitted or reflected

Answer 66

The ionization energy of hydrogen is the energy required to completely remove an electron from the hydrogen atom, i.e., to transition the electron from the ground state (n=1) to n=∞, where the electron is no longer bound to the atom.