Properties and Groups Flashcards
Why do elements in the same group of the periodic table react in similar ways?
Because their atoms have the same number of electrons in the highest occupied energy level. (the outer shell)
What’s the main differences between metals and non metals?
Metals conduct electricity whilst non metals are electrical insulators. Metals also usually have higher melting and boiling points. Non metals are more brittle. Metals lose electrons, non metals tend to gain electrons.
How many electrons are usually gained, for ions of group 5, 6 and 7 of the periodic table?
Group 5 elements gain 3 electrons. Group 6 gains 2 electrons. Group seven elements gain one electron.
Do group 1, 2 and 3 elements tend to gain or lose electrons as ions?
Lose electrons (cations).
What properties do noble gases have as monatomic gases?
They have no tendency to react and form molecules.
List 5 properties of alkali metals (Group 1)
- Very reactive and stored in oil
-Very low density
-Very soft
-very low melting and boiling points, decreasing going down
-reactivity increases going down the group
What happens when an alkali metal bonds with a non metal?
They have one electron in outermost shell, they lose it when reacting with non metals. This forms 1+ ions. The compounds made are generally white and dissolves clear in water.
What happens when an alkali metal reacts with water?
The metal floats and fizzes as hydrogen gas is produced. If the metal is potassium, it will react with hydrogen to produce a lilac flame. The reactions of alkali metals and water create a metal hydroxides that are white but are soluble in water. The solution created is clear with a high ph- when tested with universal indicator paper, the UI paper turns purple.
Describe X properties of the halogens in group 7
- They are toxic non metals
-They have coloured vapours
-They have low melting and boiling points that increase going down
-They are poor conductors of electricity
-Exist as diatomic molecules (atoms in pairs) held by covelent bonds
How do the halogens react with hydrogen?
They gain one electron to have a full outershell. Fluorine is explosive, even at -200 degrees and in the dark. Chlorine is explosive in sunlight. Bromine and iodine react with hydrogen but only over 300 degrees and with a platinum catalyst.
What is the trend of order of reactivity for a halogen?
A more reactive halogen will displace a less reactive halogen from solutions of its salts. Their reactivities decrease going down the group.
Explain the trends of electron shells going down a group a what it means for the atoms
As you go down a group, an extra electron shell is added to each element (but they all still have the same number of electrons in the outermost shell). This means the atoms get bigger. Larger atoms lose electrons more easily going down the group and gain electrons less easily going down a group.
Explain the trend of electron shells group 1.
Reactivity increases going down as atoms get bigger. This is as the distance between electron and nucleus increases, electrostatic attraction to the nucleus weakens. Electrons are then more attracted to other atoms.
Explain trend of electron shells in group 7.
Reactivity decreases going down the group. This is due to the increasing size of the atom, the shielding effect of inner electrons (more electrons in the way of the outer shells- ‘shielding’ the nucleus and reducing attraction) and the
size of the nuclear charge (how positive it is- bigger = more positive = more attraction).
Which groups are the transition elements?
2 and 3
What are the physical properties of transition elements?
- Good conductors of electricity and heat
-Hard and strong
-High densities
-High melting points
(except mercury- liquid in room temp)
What are the chemical properties of the transition elements?
-Less reactive than group 1
-Will not react with oxygen, chlorine or water as easily as alkali metals do
-Because of this, they corrode very slowly
Which compounds of transition elements form the colours; blue, pale green, dark green and pale pink?
Copper (II) sulfate is blue , Nickel (II) Carbonate is pale green, Chromium (III) oxide is dark green, Manganese (II) chloride is pale pink.
Why do compounds of transition elements often include a roman number?
Because transition elements can form more than one ion. The roman numeral indicates the charge of the ion and so which version it is.
Which two transition elements are commonly used as catalysts?
Nickel is used as a catalyst to produce margarine, Iron is used as a catalyst in the Haber process to make ammonia.
Describe the positions of particles when in a solid, liquid and gas.
Solid: Particles are closely packed together in a fixed arrangement. They vibrate but do not move from their positions.
Liquid: Particles are still close together but can move past each other. This allows liquids to flow and take the shape of their container.
Gas: Particles are far apart and move freely. They fill the entire space of their container and have high energy.
Where is energy moving to when melting and boiling, versus freezing and condensing?
In melting and boiling, energy is transferred from the surroundings to the substance. In freezing and condensing, energy is transferred from the substance to the surroundings.
Describe the changes occurring to particles that occur as a gas is cooled down into a liquid and then a solid.
Gas to Liquid (Condensation):
As the gas cools, its particles lose energy.
They move closer together and begin to attract each other.
This results in the formation of a liquid.
Liquid to Solid (Freezing):
As the liquid cools further, the particles lose even more energy.
They slow down and arrange themselves into a fixed structure.
This forms a solid.
How do elements make compounds?
Elements react together to form compounds by gaining or losing electrons or by sharing electrons.
What is Ionic and covalent bonding?
When atoms react, they make a more stable arrangement by either: sharing electrons known as covalent bonding, or transfer electrons known as ionic bonding.
Explain how atoms of Group 1 and Group 7 elements react with each other in terms of electronic structures.
As they react, each group 1 element loses one electron and the group 7 element gains an electron. Both form a more stable structure in this compound. They achieve the electronic structure of a noble gas.
What structures are created from ionic bonding?
A giant structure or giant lattice.
What happens when ions are formed?
ionic bonding. When charged ions are created. This is unlike sharing electrons in covalent bonding.
Which group never forms ions in compounds?
Group 0 and 4
Explain why potassium bromide is KBr but potassium oxide is K2O
Potassium (K) forms a 1+ ion, and bromine (Br) forms a 1- ion. In potassium bromide (KBr), one K⁺ ion bonds with one Br⁻ ion, so the ratio is 1:1, making the formula KBr.
In potassium oxide, oxygen (O) forms a 2- ion, so two K⁺ ions are needed to balance one O²⁻ ion. This gives the formula K₂O.
Explain why magnesium oxide is MgO but magnesium chloride is MgCl2
Magnesium (Mg) forms a 2+ ion. In magnesium oxide (MgO), one Mg²⁺ ion bonds with one O²⁻ ion, giving a 1:1 ratio and the formula MgO.
For magnesium chloride (MgCl₂), each chlorine (Cl) forms a 1- ion. To balance Mg²⁺, two Cl⁻ ions are needed, so the formula is MgCl₂.
Why do metal atoms tend to form positive ions and why non metals form negative ions
Metal atoms tend to form positive ions because they have few electrons in their outer shell. It’s easier for them to lose these electrons and achieve a stable, full outer shell, which makes them positively charged.
Non-metal atoms tend to form negative ions because they have more electrons in their outer shell and are close to filling it. It’s easier for them to gain electrons to complete their outer shell, making them negatively charged.
How are ionic compounds held by ionic bonding?
They are held by strong forces of attraction between oppositely charged ions.
Which groups can form ionic compounds?
Groups 1 and 7 and Groups 2 and 6
What holds a giant lattice together?
Strong forces of electrostatic attraction in all directions, from positively and negatively charged ions.
Why do giant ionic structures have high melting and boiling points?
It takes a lot of energy to break the many strong ionic bonds (the electrostatic forces of attraction specifically)
Why can solid ionic compounds not conduct electricity?
The ions are bound tightly by their electrostatic forces, so the ions are held in place which limits their vibration.
When can ionic compounds conduct electricity?
When molten or dissolved in water as their ions are then free to move.
What happens to ions in ionic solids?
The ions are fixed into position in a giant lattice. They vibrate but cannot move around so cannot conduct electricity. All ionic compounds are solid at room temperature.
What happens to ions in a molten ionic compound?
The high temperature provides enough energy to overcome the many strong attractive forces between ions. Ions are free to move around the molten compound and it can conduct electricity as ions are mobile enough to carry charge.
What happens to ions, in an ionic compound that is in a solution?
Water molecules separate ions from the lattice. Ions are free to move around the solution and it can conduct electricity as ions are mobile enough to carry charge.
Describe covalent bonding
It is what occurs when non metals react together to form stable structures. Both atoms share their electrons together in pairs of electrons. The bonds are strong and known as covalent bonds.
What two structures do non metals of covalent bonding exist as?
Either simple molecules like water or giant covalent structures like diamonds.
