Chapter 8 - The periodic table Flashcards
What is the periodic table?
The periodic table is an arrangement of elements in periods and groups and in order of increasing atomic number. The periods are the horizontal rows that show the number of shells of electrons an atoms have. The groups are the vertical columns that show how many valence electrons each atom has.
How do elements in group 1 and group 7 become stable?
Elements in group 1 will have a +1 charge as they need to lose one electron to become stable. Elements in group 7 will have a -1 charge as they need to gain one electron to become stable.
How does the metallic character of elements change across periods and group?
The metallic character of the elements decreases as you move across a period from left to right and it increases as you move down a group. This trend occurs due to atoms more readily accepting electrons to fill their outer shells. Metals occur on the left-hand side of the periodic table and non-metals on the right.
What are some characteristics of metals?
Metals undergo metallic bonding, are good conductors, basic oxides, many react with acids, are malleable and have high melting and boiling points.
What are some characteristics of non-metals?
Non-metals undergo covalent bonding, are poor conductors, acidic oxides, do not react with acids, are brittle and have low melting and boiling points.
What do elements in the same groups share?
Elements in the same group have similar chemical properties. The similarity in their chemical properties stems from them having the same number of electrons in their outer shell.
Describe some characteristics of group 1 elements, noble gases, transition elements and group 7 elements
Because there are patterns in the way the elements are arranged on the periodic table, there are also patterns and trends in the chemical behaviour of the elements and their physical properties. Some common trends include group 1 elements react very quickly with water, noble gases are unreactive, transition elements are denser than group 1 elements, reactivity decreasing going down group 7 and melting point decreasing going down group 1.
What are group 1 metals?
Group 1 metals are also known as alkali metals as they form alkaline solutions with high pH values when reacted with water. Group 1 metals consist of lithium, sodium, potassium, rubidium, caesium and francium. They all contain 1 valence electron.
What are the characteristics of group 1 metals?
They are soft and easy to cut. As you move down the group, they get softer and denser. (Sodium and potassium do not follow the trend in density. They have shiny silvery surfaces when freshly cut. They conduct heat and electricity. They have low melting points, and the melting point decreases as you move down the group. Reactivity increases as you move down the group.
What are group 7 elements?
Group 7 halogens include fluorine, chlorine, bromine and iodine which are diatomic non-metals. They form halide ions by gaining one more electron to complete their outer shell.
What are the characteristics of group 7 elements?
As you go down the group, density increases, reactivity decreases and the melting and boiling point increases.
How is chlorine, bromine and iodine seen at room temperature?
At room temperature, chlorine is a pale yellow/green gas, bromine is a red/brown liquid and iodine is a grey/black solid.
What are transition elements?
Transition elements are found in the centre of the period table. They contain ions with variable oxidation numbers as they can lose a different number of electrons. E.g. iron can lose 2 electrons to form Fe2+ or it can lose 3 electrons to form Fe3+. Compounds containing transition elements in different oxidation states will have different properties and colours.
What is a halogen displacement reaction?
A halogen displacement reaction occurs when a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide. E.g. if you add chlorine solution to colourless potassium bromine, chlorine will displace bromine and for an aqueous solution of the metal and bromine. The least reactive halogen always ends up in the elemental form.
What are the characteristics of transition elements?
They have high densities, high melting points, form coloured compounds and often act as catalysts as elements and in compounds.
What are noble gases?
Noble gases are group VIII elements.
What are the characteristics of noble gases?
They are unreactive, monatomic, colourless gases. They have stable, full outer shells meaning they do not need to lose or gain any electrons, thus making them unreactive.
