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Chemistry > Trends in the Periodic table.2 > Flashcards

Trends in the Periodic table.2 Flashcards

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1
Q

What are the elements in the periodic table arrangesd in order of

A

increasing atomic number

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2
Q

what are the vertical columns in the periodic table called

A

groups

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3
Q

horizontal rows

A

periods

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4
Q

what do elements in the same period have

A

have the same number of shells

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5
Q

what do elements in the same group have i common

A

have the same number of electrons in their outer shell/ valence shell

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6
Q

What is the name of group 1

A

Alkali metals

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7
Q

what valency do the Alkali Metals have?

A

valency of 1

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8
Q

Describe the reactivity of the Alkali Metals

A

highly reactive, before becoming more reactive going down the group

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9
Q

are Alkali metals found freely in nature?

A

not found freely in nature, only found in compounds with other elements

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10
Q

why are the alkali metals highly reactive

A

They do not satisfy the octet rule- they only have one electron in their valence shell.
In order to satisfy the octet rule they readily lose this electron when they react and form a monopostive ion.

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11
Q

why does reactivity of the alkali metals increase going down group 1

A

the atomic radius increases

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12
Q

List 3 properties of Alkali metals

A

soft metals- can be cut with a knife
low melting points and boiling points.
Have low densities - float on water

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13
Q

Describe the reactions of the alkali metals with oxygen

A

They react rapidly with oxygen to form a metal oxide.
for this reason they are stored in oil

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14
Q

what does an alkali metal + oxygen make

A

metal oxide

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15
Q

Describe the alkali metals reaction with water

A

Float on water.
React vigorouly with water.(reaction becomes more violent going down the group)
causes fizzing with water
produces a metal hydroxide and hydrogen gas

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16
Q

write a reaction for alkali metals with water

A

metal + water –> metal hydroxide + hydrogen

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17
Q

Demonstration of the reaction of the alkali metals lithium, sodium and potassium with water

A

all three metals float on water
each metal reacts vigorously with water
Fizzing occours due to hydrogen gas produced. This gas will ignite with a pop.
the reaction becomes more violent as the metals futhers down the group are added : sodium may spark and potassium catches fire.

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18
Q

what is group 2 called

A

The alkaline Earth Metals

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19
Q

what valency do the alkali earth metals have

A

have a valency of 2

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20
Q

describe the reactivity of the alkali earth metals

A

reqctive - but not as reactive as the alkali metals. become more reactive going down the group.

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21
Q

why are the alkaline earth metals reactive

A

they do not satisfy the octet rule - they have two electrons in their outwer shell in order to satisfy the octet rule, they readily lose these electrons when they react and form a dipostive ion (+2)

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22
Q

why does the reactivity of th alkaline earth metals increase going down group 2

A

the atomis radius increases

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23
Q

describe the reactivity of the alkaline earth metals with oxygen

A

the alkali metals react with oxygen to form a metal oxide, not as rapid as the alkali metals with oxygen

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24
Q

write a equaltion for the alkali earth metals reaction with oxygen

A

metal + oxygen –> metal oxide

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25
Q

describe the reactivity of the alkaline earth metals with water

A

they react with water to form a metal hydroxide and hydrogen gas.
Not as rapid or as vigorous a reaction as the alkali metals with water

26
Q

write equation describing the reaction of alkaline metals with water

A

metal + water —> metal hydroxide + hydrogen

27
Q

How is a transition metal identifies from its s,p configuration?

A

transition metals form at least one ion which has an incompelete 3d sublevel

28
Q

Describe 3 features of Transition elements

A

they have variable valencies (Fe2+ or Fe3+)
they form compounds
they are excellent catalysts

29
Q

What is a catalyst

A

a substance that alters the rate of a chemical reaction without being used up in the reaction

30
Q

what elements are in the transition metal block but are not transition metals, and why?

A

Scandium and Zinc are not transition elements.
They do not have vairable valencies.
their compounds are white
they do not act as catalysts

31
Q

what is group 7 called

A

The halogens

32
Q

what valency do the Halogens have

A

valency 1

33
Q

describe the reactivity of the Halogens

A

have seven electrons in their outer shell and are very reactive.They become less reactive going down the group. (form diatomic molecules - two atoms joined by a covalent bond)

34
Q

why are the halogens reactive

A

They do not satisfy the octet rule - they have seven electrons in their valence shell. In Order to satisfy the octet rule, they gain one electron when they react and form a momonegative ion

35
Q

why does the rectivity of the halogens descrease going down group 7

A

the atomic radius increases

36
Q

what intermolecular forces occour between halogen molecules?

A

van der waals

37
Q

Comment on the boiling points on the halogens

A

halogen molecules are non-polar - have weak van der waals forces between their molecules - have low boiling points.
As the molecules mass increases, the strnght of the intermolecular forces increases.
Fluorine (F2) and Chlorine (Cl2) are gases at room temperature
- Bromine (Br2) is a volatile liquid at room temperature
- Iodine (I2) is a volatile solid at room temperature

38
Q

what is group 8 called

A

the nobel gasses

39
Q

what valency do the noble gasses have

A

valency of 0

40
Q

describe the reactivity of the halogens

A

they have eight electrons in their outer shell - this is a stable arrangement of electrons do not gain, lose, or share electrons - already satisfy the octet rule. Makes then very inert and safe to use.

41
Q

Define atomic radius / convalent radius

A

half the distance between the nuclei of two atoms of the same element joined by a single covalent bond

42
Q

State and explain the trend in atomic radii values (covalent radii) across a period of the periodic table

A

Atomic radii values decrease going across a period (Atoms get smaller)
The effective nucler charge increases- more protons in the nucleus means there is an increasng attraction between the nucleus and electrons in the outer shell, and the atom is being “pulled smaller”

43
Q

State and explain the trend in atomic radii ( covalent radii) down a group of the periodic table

A

atomic radii values increase going down a group (atoms get larger). An additional shell of electrons is added on

44
Q

Why is establishing an atomic covalent radius for the noble gasses problematic

A

The noble gasses satidy the octet rule- they do not gain, lose or share electrons so do not form bonds with other elements

45
Q

What is electronegativity

A

the measure of reltive attraction an atom has for a shared pair of electrons in a covalent bond

46
Q

state and explain the trend in electronegativity values across a period of the periodic table

A

electtronegativity calues increase going across a period.
1. The atomic radius decreases - pair of electrons in the covalent bond become closer to the postive nuclear charge
2. the effective nuclear charge increases- more protons in the nucleus means there is an increasing attracting between the nulceus and electrons in the covalent bond.

47
Q

State and explain the trend in electronegativity values down a group of the periodic table.

A

Electronegativity values decrease going down a group.
1 the atomic radius increases- pair of electrons in the covalent bond become futher from the postive nuclear charge.
2. No increase in effective nuclear charge due to extra shell- electrons in covalent bond are more shielded from the nucleus.

48
Q

Why do the noble gasses not have electronegative values

A

the noble gases satisfy the octet rule- they do not gain, lose, or share electrons so do not form bonds with other elements.

49
Q

ionisation energy

A

the minimum energy required to remove the most loosely boind electron from an atom or ion

50
Q

first ionisation energy

A

the minimim energy required to remove the most loosely bounf electron from a netural gaseous atom in the ground state

51
Q

What is the first, second and third ionisation energy of potassium

A

K(g) —-> K+(g) + e-
K+(g) —> K2+ (g) + e-
K2+(g) —> K3+ (g) + e-

52
Q

what is used to mesure ionisation energy

A

kilojoules per mole

53
Q

State and explain the trend in first ionisation energy values across a period of the periodic table

A

the first ionisation energy values generally increase going across a period.
1. atomic radius decreases - the electron being removed becomes closer to the postive nuclear charge.
2. The effectve nuclear charge increases - more protons in the nucleus means there is an increasing attraction between the nucleus and the electron being removed.

54
Q

State and explain the trend in first ionisation energy values down a group of the periodic table

A

First ionisation energy values decrease going down a group.
The atomic radius increases - electrons removed futher from the postive nuclear charge.
No increase in effecive nuclear charge due to an extra shell- most loosley bound electron is screened from the nucleus

55
Q

Explain the exceptions to the general trend in energy values across a period

A

small decreases in ionsiation energies are due to electrons being removed from full sublevels, and half- full sublevels will require energy as these are high stability configurations

56
Q

Explain the large substantial energy decreases going from one period to another

A

it takes substiantially less energy to remove an electron from a shell futher from the nucleus - this explains why there are large decreases in first ionisation energy going from one period to another

57
Q

define second ionisation energy

A

the minium energy required to remove the most loosly bound electron from a postive ion

58
Q

Give two reasons why the second ionisation energy of an element is a is always greater than the first

A

1- the second electron is being removed from a postive ion- the effective nuclear charge has incresed so there is greater sttraction between the electron being removed and the nucleus

2-The atomic radius has decreased in the postive ion - the second electron being removed is closer to the postive nuclear charge

59
Q

How does looking at successive ionisation energy values for an element provide evidence for the exitance of energy levels

A

when attemption to remove an electron from a new energy level, a substantially higher amount of amount of energy is required.
looking at the number of substantial increases in ionisation energy will show how many energy levels are occupies by electrons in the atom

60
Q

What other expeirmental evidence expect for ionisation energy do we have for the exitance of energy leves in atoms

A

line emission spectra

Chemistry (27 decks)

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