In this chapter, we explore the relationship between the electron configurations of the elements, as reflected in their arrangement in the periodic table, and their physical and chemical properties. Created by Sir William Crookes (1832–1919), the spiral represents the relationships between the elements and the order of evolution of the elements from what he believed to be primal matter. Chapter 6 'The Structure of Atoms' ended with the observation that, because all the elements in a column have the same valence electron configuration, the periodic table can be used to find the electron configuration of most of the elements at a glance.Ĭrookes’s Spiral Periodic Table, 1888. Thus because of their periodic similarities in electron configuration, atoms in the same column of the periodic table tend to form compounds with the same oxidation states and stoichiometries.

In contrast, the alkali metals have a single valence electron outside a closed shell and readily lose this electron to elements that require electrons to achieve an octet, such as the halogens. Because of their filled valence shells, the noble gases are generally unreactive. These closed shells are actually filled s and p subshells with a total of eight electrons, which are called octets helium is an exception, with a closed 1 s shell that has only two electrons. For example, the noble gases have what is often called filled or closed-shell valence electron configurations. In using this model to describe the electronic structures of the elements in order of increasing atomic number, we saw that periodic similarities in electron configuration correlate with periodic similarities in properties, which is the basis for the structure of the periodic table. In Chapter 6 'The Structure of Atoms', we presented the contemporary quantum mechanical model of the atom. Gethin: So, the further down the table you go the more reactive they become.Chapter 7 The Periodic Table and Periodic Trends So, the reason we didn't see the reactions of those last three metals is that they are so reactive the explosion would be far too big. Miss Armit: No, it's the second rarest element on Earth. That's not an element that you hear a lot of. We saw there lithium, then sodium and then potassium, but you didn't see rubidium, caesium and francium. As you can see the metal's get increasingly more reactive as you go down this group. Gethin: It's fair to say that you love the Group 1 metals, don't you. Well, sodium is below lithium in group one and the reactivity of the alkali metals increases as you go down the group, so potassium is even more reactive. So let's try it with another Group 1 metal - sodium.Īs you can see it reacts far more vigorously then lithium. And can you see the little purple trail there? That universal indicator is showing us that the water now contains an alkali in this case - lithium hydroxide.

It's transferring its energy to its surroundings by heating. Well, you can see it's reacting with the water straight away - it's steadily fizzing away there. And if I put some universal indicator in, like this, you'll see that it's green and that means it's neutral.īut let's see what happens when we put the lithium in. And do you see how quickly it tarnishes, how quickly it's changing colour? Here we've got some water. Here I've got some lithium and I'm just going to cut a little bit off. When a Group 1 element reacts with water it produces a metal hydroxides solution and hydrogen gas. They're soft and shiny when freshly cut, but they quickly tarnish as the metal reacts with oxygen in the air. Let's take a look at some Group 1 metals then - also known as alkaline metals.įran: Group 1 elements are called the alkali metals. Gethin: And today we're going to be looking at the periodic table.

Reactivity trend across periodic table