C1 Flashcards
What does the nucleus contain?
- its in the middle of the atom
- it contains protons and neutrons
- it has a positive charge because of the protons
Why are atoms neutral?
Because the protons and electrons cancel each other out
What is a compound?
It is when atoms combine with other atoms to form compounds
What did john dalton do?
He described atoms as solid spheres and said that different spheres made up the different elements.
What did J J Thomson do in 1897?
He concluded that the atoms weren’t solid spheres and his measurements of charge and mass showed that an atom must contain smaller negatively charged particles - electrons. He then changed the ‘solid sphere’ idea and introduced the new theory known as the plum pudding model.
What is J J Thomphsons plum pudding model?
The plum pudding model showed that the atom as a ball of positive charge with electrons stuck in it.
What are isotopes?
Isotopes are different forms of the same element which have the same amount of protons but a different amount of neutrons.
What does the atomic number show you in a atom?
It shows how many protons there are
What does the mass number tell you about an atom?
It tells you the total number of protons and neutrons in the atom
What did Rutherford do? And how did he do it?
He showed that the plum pudding model was wrong. He did this by firing positively charged alpha particles at a thin sheet of gold and more than expected of particles got deflected back but most of them went through because of the nucleus being positive and reppeling ++ and the electrons are - and alpha are + so it went through the empty space. Therefore the plum pudding theory couldn’t be right.
What was Bohr’s nuclear model?
Scientists thought that the electrons in a ‘cloud’ like Rutherford said is wrong because then the electrons would be attracted to the nucleus and then the whole atom would collapse. So Bohr said that electrons were contained in shells and that the electeons orbit the nucleus in fixed shells and aren’t anywhere inbetween. Each shell is a fixed distance from the nucleus .
How were protons found out?
Rutherford found out that the nucleus can be divided into smaller particles and these had the same charge as a hydrogen nucleus. These particles became known as protons
Who found out that there were neutrons in the nucleus?
Chadwick
In the early 1800 what were elements arranged by?
Atomic weight
What is an ion?
An ion is a charged atom
