8 The Periodic Table Flashcards
Periodic table
A table that lists all the elements in ascending order of atomic number. Also organised by groups and periods, which detail the electronic configuration of the elements.
Metal
An element with atoms that are metallic bonded and tends to lose electrons during reactions.
Non-metals
An element that is not a metal. Tends to accept electrons during reactions.
Group
A term used in chemistry to describe a column in the Periodic Table. The elements within a group have similar chemical properties as they all have the same number of electrons in the outer shell.
Period
A term used in chemistry to describe a horizontal row in the Periodic Table. The period number tells you how many electron shells an element has.
Noble gas
Elements from Group VIII of the Periodic Table. They are unreactive as their outer shells are full of electrons.
Nucleon number
The combined number of protons and neutrons in the nucleus of an atom. The nucleon number also represents the mass of an atom and is also known as the mass number.
Proton number
The number of protons found in the nucleus of an atom. The number of protons in its nucleus defines an atom. Also called the atomic number.
Properties of metals
Metals
Large atomic radius
Conduct heat and electricity
Have a range of melting point values
Malleable and ductile
Shiny
Properties of non-metals
Non-metals
Smaller atomic radius
Do not conduct heat or electricity*
Generally low melting point values
brittle
Dull
Metaloids
Elements that display properties of both metals and non-metals.
Relationship between Group number and Period number with electron configuration
The period number is the same as the number of electron shells that an element has.
The group number of an element is the same as the number of electrons it has in its outer shell.
Ions form when atoms lose or gain electrons.
Metal atoms lose electrons to form positively charged ions.
Non-metal atoms gain electrons to form negatively charged ions.
Covalent radius
A measure of the radius of an atom. Each element has a different nucleus and electron configuration so the size of the atom differs. Plural is covalent radii.
Why covalent radius increases as you go down a group?
Why covalent radius decreases as you go across a period?
You would expect the covalent radius to increase as you go down a group as the number of shells of electrons increases. Each time a new outer shell is added, the radius increases.
As you go across a period, electrons fill up the same electron shell and the number of protons in the nucleus increases. This increases the strong attractive force and pulls the electron shells closer to the nucleus.
Alkali metals
Metal elements from group I of the Periodic Table. Readily form alkaline hydroxides on reaction with water.
Properties of alkali metals
As the elements in Group I share the same number of electrons in their outer shell
The time taken for a freshly cut element to tarnish decreases going down the group, showing that the reactivity increases going down the group.
They all have low densities. Some will even float on water.
The melting points are relatively low.
They metals react vigorously with water to produce a metal hydroxide and hydrogen gas.
Relationship between density and Alkali metals
Lithium, sodium and potassium are less dense than water, so they float on water when reacting with it. The pattern is for the density of the Group I elements to increase going down
Relationship between Melting point and Alkali Metals
The melting point for lithium is quite low for a metal. The pattern going down the group is for the melting point to decrease
Alkali metals reaction with metals
All Group I metals react vigorously with water to produce a metal hydroxide and hydrogen gas.
Lithium reaction with water
The reaction can be seen on the surface of the water. This is because lithium is less dense than water. As hydrogen gas is given off by the reaction, effervescence can be seen. The piece of lithium will often move around on the surface of the water due to the hydrogen gas being given off. The water will become slightly alkaline because of this reaction.
Sodium reaction with water
The reaction of sodium with water is very similar to the reaction of lithium, however, the reaction is much more vigorous and more heat is given off. The piece of metal will move around the surface of the water faster and the reaction will usually finish quite quickly.
Potassium reaction with water
When potassium reacts with water, it produces enough heat to ignite the hydrogen gas produced. The flame produced is a lilac colour. As the reaction is so vigorous, the potassium may begin to hop around on the surface of the water.
Halogens
Elements belonging to Group VII in the Periodic Table.
Trends in the halogens in colour
The trend down the group for colour is increasing darkness.
Chlorine is a green gas.
Bromine is a dark red liquid.
Iodine is a dark purple solid.
Density in halogens
The trend down the group is for increasing density.
Fluorine and chlorine are only found as a gas at room temperature.
Bromine exists as a liquid and a vapour, where iodine is found as a solid.
Melting points in halogens
As you go down the group, the melting points increase.
Reactivity of the halogens
The reactivity of halogens decreases going down the group. This is because, with seven electrons in the outer electron shell, halogens react by attracting an electron to gain a full outer shell. As we move down the group, the ability of the elements to attract an extra electron to complete the outer shell weakens. This means that chlorine is much more reactive than iodine and fluorine is the most reactive halogen.
Displacement reaction
A reaction where a less reactive element is removed from a compound by a more reactive element.
Halide salts
Salts formed from halogens such as fluorine, chloride, bromide and iodide.
An example of a displacement reactions of halogens with other halide ions
An example of this would be with potassium iodide. If we add chlorine gas, as chlorine is more reactive, the iodine will be displaced from the compound to form potassium chloride.
potassium iodide + chlorine → potassium chloride + iodine
2KI(aq) + Cl2(g) → 2KCl(aq) + I2(aq)
This is an example of a redox reaction
Reactivity series
A list in which elements are ordered according to their reactivity. The most reactive elements are listed at the top.
Noble gases
Elements from Group VIII of the Periodic Table. They are (unreactive) as their outer shells are full of electrons. They are colourless gases that exist as single atoms, which is why they are sometimes referred to as (monatomic).
The appearance of the halogens at RTP
Chlorine, a pale yellow-green gas
Bromine, a red-brown liquid
Iodine, a grey-black solid
Transition metals
Metal elements from the central block of the Periodic Table.
They are elements that have ions with variable oxidation numbers, including iron(ll) and iron(lll)
Properties of transition metals
Physical
have high densities
have high melting points
High strength
Chemical
form coloured compounds
often act as catalysts as elements and in a compound
Have ions with variable oxidation numbers
Calcium reaction with water
For calcium the solid metal would sink, and bubbles would be produced on the surface of the metal but they would be produced much less slowly. As the metal disappears the solution will become cloudy as calcium hydroxide is insoluble.
Magnesium reaction with steam
Magnesium burns in steam to produce white magnesium oxide and hydrogen gas.
Magnesium, iron and zinc reaction with dilute acid
With magnesium, bubbles would form on the surface and the metal would slowly disappear. With zinc, bubbles would form but very slowly. Iron would react so slowly it may be difficult to observe.
