Groups in periodic table Flashcards
group one are also known as
group seven are also known as
group 0 are also known as
alkali metals
halogens
noble gases
Recall that alkali metals:
are
have relatively low
soft
melting points
How does lithium react with water
Lithium (Li) and Water:
Lithium floats on water, fizzes gently, and disappears as it reacts.
The reaction is relatively slow and generates heat, but the heat is not enough to ignite the hydrogen.
How does sodium react with water
Sodium (Na) and Water:
Sodium melts into a ball that moves around on the water’s surface, fizzing vigorously, and then disappears.
The reaction is more vigorous than lithium’s and generates enough heat to melt the sodium.
How does potassium react with water
Potassium (K) and Water:
Potassium melts and floats on the water, moves rapidly around, and self-ignites, producing sparks and a lilac flame.
The reaction is very vigorous, generating enough heat to ignite the hydrogen gas and produce a lilac flame.
What happens to reactivity as you go down the alkali metals and why
Increases
The reactivity of Group 1 elements increases as you go down the group because:
the atoms get larger
the outer electron gets further from the nucleus
the attraction between the nucleus and outer electron gets weaker – so the electron is more easily lost (less shielding)
Explain why the noble gases are chemically inert,
compared with other elements, in terms of their electron configurations.
The atoms of noble gases already have complete outer shells, so they have no tendency to lose, gain, or share electrons.
Explain how the uses of noble gases depend on their inertness, low density and/or non-flammability
Inertness makes them suitable for applications like shielding gases in welding,
while low density allows their use in balloons and airships.
Their non-flammability makes them safe lifting gases and suitable for preventing metal wire burning in lightbulbs.
Describe the pattern in the physical properties of some noble gases and use this pattern to predict the physical properties of other noble gases
Their bp/mp increases the more you go down the group due to inc atomic size/mass
Recall the colours and physical states of chlorine, bromine and iodine at room temperature.
Chlorine: Yellow-Green Gas
Bromine: Red-brown liquid
Iodine: Dark purple vapour when warmed up otherwise a shiny grey crystal (solid)
Describe the pattern in the physical properties of these three halogens and use this pattern to predict the physical properties of other halogens.
melting and boiling points, color intensity, and
density increase as you move down the group.
This trend can be used to predict the properties of other halogens, such as astatine. For example, astatine, below iodine, would likely be a solid with a higher density and darker color.
Describe the chemical test for chlorine,
To test for chlorine, use damp blue litmus paper. The blue colour will turn to red and then to white.
Chlorine gas reacts with water to produce an acidic solution which is also an effective bleach. This explains how the test for chlorine works.
The acidic solution formed on the damp litmus paper turns the indicator red. Then the bleach turns the red colour to white.
Do halogens become more or less reactive down the periodic table and why
Going down group 7:
the atoms become larger
the outer shell becomes further from the nucleus
the force of attraction between the nucleus and the outer shell decreases
an outer electron is gained less easily
the halogen becomes less reactive
What is a displacement reaction
A more reactive halogen can displace a less reactive halogen from solutions of its salts. For example, chlorine is more reactive than iodine. A solution of chlorine can displace iodine from potassium iodide solution:
chlorine + potassium iodide → potassium chloride + iodine
Cl2(aq) + 2KI(aq) → 2KCl(aq) + I2(aq)
You add chlorine water to potassium iodide and because chlorine is more reactive it will displace it
Why are displacement reactions redox reactions
Cl2(aq) + 2Br-(aq) → 2Cl-(aq) + Br2(aq)
This is a balanced ionic displacement reaction equation which can be rewritten into 2 smaller reactions
Cl2(aq) + 2e- → 2Cl-(aq), (reduction)
2Br-(aq) → Br2(aq) + 2e-, (oxidation)
