![]() 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. Because its 2n shell is filled, it is energetically stable as a single atom and will rarely form chemical bonds with other atoms.Gethin: And today we're going to be looking at the periodic table. For instance, lithium ( Li \text Ne start text, N, e, end text ), on the other hand, has a total of ten electrons: two are in its innermost 1 s 1s 1 s 1, s orbital and eight fill the second shell-two each in the 2 s 2s 2 s 2, s and three p p p p orbitals, 1 s 2 1s^ 2 1 s 2 1, s, squared 2 s 2 2s^ 2 2 s 2 2, s, squared 2 p 6 2p^6 2 p 6 2, p, start superscript, 6, end superscript. Elements in the second row of the periodic table place their electrons in the 2n shell as well as the 1n shell. After the 1 s 1s 1 s 1, s orbital is filled, the second electron shell begins to fill, with electrons going first into the 2 s 2s 2 s 2, s orbital and then into the three p p p p orbitals. The second electron shell, 2n, contains another spherical s s s s orbital plus three dumbbell-shaped p p p p orbitals, each of which can hold two electrons. Hydrogen and helium are the only two elements that have electrons exclusively in the 1 s 1s 1 s 1, s orbital in their neutral, non-charged, state. On the periodic table, hydrogen and helium are the only two elements in the first row, or period, which reflects that they only have electrons in their first shell. This is written out as 1 s 2 1s^ 2 1 s 2 1, s, squared, referring to the two electrons of helium in the 1 s 1s 1 s 1, s orbital. Helium has two electrons, so it can completely fill the 1 s 1s 1 s 1, s orbital with its two electrons. This can be written out in a shorthand form called an electron configuration as 1 s 1 1s^ 1 1 s 1 1, s, start superscript, 1, end superscript, where the superscripted 1 refers to the one electron in the 1 s 1s 1 s 1, s orbital. Hydrogen has just one electron, so it has a single spot in the 1 s 1s 1 s 1, s orbital occupied. The 1 s 1s 1 s 1, s orbital is the closest orbital to the nucleus, and it fills with electrons first, before any other orbital. The first electron shell, 1n, corresponds to a single 1 s 1s 1 s 1, s orbital.
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