Chemistry - Trends in the Periodic table Flashcards Part 1

Groups are vertical column. Elements in the same group have the same number of electrons in their outer shell

A period is a horizontal row. Elements in the have same number of shells

Half the distance between the nuclei of two atoms of the same element that are joined together by a single covalent bond

The force of attraction between the positive protons in the nucleus and the negative electrons in the outer shell.

Increases

As you do down a group, each elements has one more shell of electrons than the previous. The negative outer electrons get further away from the positive nucleus. Screening effect increases

The increase in nuclear charge as you go down a group is lessened by a screening effect. The electrons in the inner shells screen the outer electrons from the positive charge in the nucleus

Decreases, There a increase in effective nuclear charge, No increase in screening effect

Number of protons increase, number of shells stay the same so the increase in effective nuclear charge,so there is a greater attractive force on the outer electrons

The minimum energy required to completely remove the most loosely bound electron from a neutral gaseous atom in its ground state

Decreases, Increasing screening effect. Increasing atomic radius

Increases, Increasing nuclear charge, Decreasing atomic radius

These elements would have full/ half full sublevels. Full or half filled sublevels give an atom extra stability so more energy is required to remove an electron

The energy required to remove an electron from an ion with one positive charge in the gaseous state.

X+(g) —-> X2+(g) + e-

( small 2+)

X= element

g= state of matter

K(g) —-> K+(g) + e-

K+(g) —> K2+ (g) + e-

K2+(g) —> K3+ (g) + e-

Decreased shielding effect

The relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond

Electronegativity decreases going down a group.

1.increasing atomic radius

2. Increasing screening effect.

Electronegativity increases going across a period. 1 Increasing effective nuclear charge, 2 Decreasing atomic radius

depends on their type of chemical bonding. How an element forms a bond is due to the number of electrons in the outer shell

They have a low ionization energy, the readily lose the single electron in their outer shell

They are found in compounds, not free in nature itself

Easier, because: The atomic radius increases, Screening effect increases

They all react vigorously with cold water. Hydrogen gas is given off, metal hydroxide is produced, Speed and violence of the reaction increases as you go down a group- increased reactivity

Lithium floats, fizzes steadily and become smaller until it eventually disappears

The sodium melts to form a ball that moves around on the surface of the water. It fizzes rapidly, the hydrogen produced may produce a orange flame before the sodium disappears

(element) + water ---> (element) hydroxide + hydrogen

(element) + H2O ---> (element)OH + 1/2 H2

When Alkali metals are cut they initially appear shiny grey but quickly become dull and white as they react with oxygen in the air- this is known as tarnishing

Lithium tarnishes slowly due to its relatively slow reaction with oxygen

Tarnishes quicker than lithium, its more reactive then Lithium

Potassium tarnishes so quickly its difficult to see potassium is actually a shiny metal.

( element) + Oxygen --> (element) oxide

2(element) + 1/2 O2 ---> (element)2O

The octet rule, 8 electrons in the outer shell

It gains one electron

Decreases, The atomic radius increases, The effective nuclear charge decreases

Displacement reactions

When chlorine( as a gas or dissolved in water), is added to sodium bromide, the chlorine takes the place of the bromine. The chlorine is more reactive than bromine

Chlorine+ sodium bromide-> sodium chloride +bromide

A more reactive halogen displaced a less reactive halogen from a solution of one of its salts.the electronegativity decreases

A chemical which causes another chemical to lose an electron and become positivity charged

One reactant has lost an electron and the other has gained an electron

The halogens are very reactive elements, they are too unstable to exists in a nature in a uncombined form.They often react by taking an electron from another element, they act as oxidising agents. The smaller a halogen atom, the stronger oxidising agent it is.

F >Cl >Br >I >At

Pale green

Yellow/ orange

Brown/red

Colourless

Colourless

Colourless

A molecule that is made up of two atoms of the same or different elements

aqueous solution

Oxidation Is Loss, Reduction Is Gain