The periodic table Flashcards
How are the elements arranged in the modern periodic table?
In order of increasing atomic number.
What is a period and how do elements in a period relate to each other?
- A horizontal row in the periodic table.
- Elements in the same period have different electron configurations and different orbitals but the outer electrons are in the same quantum shell.
- Elements in the same period show a trend in physical and chemical properties.
- This trend is called periodicity.
What is a group and how do elements in a group relate to each other?
- A vertical column down the periodic table.
- Element in the same group have the same number of electrons in the outer shell and the same orbitals but on different quantum shells.
- Elements in the same group show similar physical and chemical properties since they have similar electron configurations.
What is the trend in atomic structure across a period?
Across a period, first ionisation energies increase. This is because the nuclear charge is increasing, so the force of attraction from the nucleus on the electrons is also increasing. However, the additional electrons are also going into the same quantum shell so they experience the same amount of electron shielding. Distance actually decreases as the atomic radii decreases across a period which further increases force of attraction between nucleus and electron. All this means that the effective nuclear charge increases across a period so first ionisation energies also increase.
Also as a result of the increase in effective nuclear charge, the electrons get pulled more and more inwards across a period so atomic radii decreases across a period.
What is the trend in atomic structure down a group?
Down a group, first ionisation energies decrease despite the increases in nuclear charge. This is because as you go down a group, the atoms of elements are increasing in size by one quantum shell each time. This means that the outer electrons of each atom is experiencing one more shell worth of electron shielding as well as well as an increase in distance from the nucleus. All this counteracts the increased nuclear charge and thus first ionisation energies decrease.
Atomic radii also increases down a group as a result of the increased shielding. this means that the electrons do not experience as strong an effective nuclear charge and are not pulled in as closely as each other. This results in the atomic radii increasing down a group.
What are the trends in reactivity for group 2 metals?
As you go down the group, the metals become more reactive.
What is the trend in solubility of group 2 hydroxides?
Hydroxides become more soluble as you go down the group and the solutions formed increase slightly in pH. However, the typical pH of any group 2 hydroxide solution is 10-12.
What is the trend in thermal decomposition of group 2 carbonates?
Group 2 carbonates decompose more easily as you move up the group. I.e. as you move down the group, higher temperatures are required to decompose the carbonate.
What is the common name for calcium carbonate?
Limestone.
What is the common name for calcium oxide?
Quicklime.
What is the common name for calcium hydroxide?
Slaked lime.
What is the use of calcium hydroxide?
To neutralise acidic soil.
What is the use of magnesium hydroxide?
Used in ‘milk of magnesia’ to neutralise stomach acid in indigestion.
