Trigger words: half life
Indicator sentences: What does that mean ?
Negotiation parts: that , that 's how long it takes for half of the radioactive isotopes to disappear . Great , yeah , that 's a wonderful definition .
Trigger words: isotopes
Indicator sentences: what 's an isotope
Negotiation parts: Erm is it , It 's not an atom but it 's You could n't break say a piece of uranium or into an atom , but you could break it up into an isotope . An isotope is say several atoms put togetherNo .It 's like a molecule is it ?[UNCLEAR] like a molecule . Erm Think of two types of uranium , U two three five and U two three eight . They 've got a different atomic weight , cos they 've got a different number of neutrons , but they got the same number of protons and they 've got the same pattern of electrons , and the pattern of those outer electrons is what decides its chemical properties . So if you did a few chemical test on U two three five , U two three eight , you would n't be able to tell the difference . [UNCLEAR] same thing . And they 're called isotopes , of the same element . the only difference in the isotopes is one 's got a few extra neutrons . So that 's that 's basically what an isotope is , it 's a an element that has . Or isotopes of an element , they have the same chemical properties , they have the same outer structure and very much the same inner structure apart from one 's got a few extra neutrons .
Trigger words: catalyst
Indicator sentences: What 's a catalyst ?
Negotiation parts: Er it speeds up a reaction , it is n't used in the reaction , it just speeds it up . What do you mean by It is n't used in the reaction ? Erm it does n't it 's not necessarily needed for the reaction , it the reaction will still happen without it . The reaction could happen slowly without it generally Yeah . (3) but it 's a it makes the reaction a whole lot faster . It 's not used in great quantities in the reaction . Right it 's usually only a small quantity needed , because although it is it 's used it 's continually sort of restored . So it 's Erm I mean some people say , quite wrongly , that it 's something that does n't take any part in the reaction but speeds it up , but how can it do that . It does take a part in the reaction but it keeps getting returned back to its original state .
Trigger words: reversible reaction
Indicator sentences: What 's a reversible reaction ?
Negotiation parts: Erm it 's a reaction , say you put two chemicals together .Mm .they 're not stuck together you can separate them again , it 's The reaction can go both ways .Right the reaction goes both ways . A lot of chemical reactions are actually reversible , but the tend to be mainly going very much in one direction , so we just say we just write it as though it only went in one direction .