OCR GCE Chemistry - Atoms and Reactions


What are the 4 stage of scientific process?






Why are laboratories used in controlled experiments?

-Control variables


What are the 3 types of particle atoms are made of?

-Protons, neutrons and electrons


What do electrons whizz around in?



Where is most of the mass of the atom concentrated?



Where is most of the space of the atom found?



Why is relative mass and relative charge for subatomic particles?

-They are so small


What is the word used to describe the mass of an electron. What is its actual mass?




What is the mass of 2 nucleons?



What is the charge of a nucleus of an atom?



What is the charge of a whole atom?



What charge will an atom have it loses 3 electrons?



What property is represented by the letter A for an atom?

-Mass (nucleon) number


What letter is used to show the Atomic (proton) number of an element?



Lithium has 7 nucleons and 3 protons. How many neutrons and electrons does it have?

-4 neutrons and 3 electrons


If an element has different numbers of protons and electrons, what is it called?



Negative ions have **** electrons than protons



Positive ions have more ******* than electrons



What is an isotope?

-Atom of the same element with different numbers of neutrons but same number of protons


What decides the chemical properties of an element?

-Number and arrangement of electrons


Why do isotopes have the same chemical properties as its own element?

-Same electron configuration


What may differ about isotopes of an element? Give examples

-Physical properties

-Densities, rates of diffusion


Why do the physical properties of an isotope differ?

-Physical properties depend more on the mass of the atom


What is the name given to what we think an atom looks like now?

-Accepted model


Why is the accepted model assumed as true?

-Fits all the observations and evidence so far, until someone shows that it’s incomplete or wrong


Where did the word ‘ATOM’ originate from? What does it mean?

-‘Atomos’ in Greek



What did the Ancients Greeks and John Dalton in 19th century think about atoms?

-They were indivisible particles (solid spheres), with different spheres for different elements


Who concluded in 1897 that atoms were not just solid spheres?

-JJ Thompson



How did JJ Thompson prove that atoms were not just solid spheres?

-His measurements of charge and mass showed that an atom must contain even smaller, negatively charged  particles.


What did JJ Thompson call the negatively charged particles? What do we call them now?




What was JJ Thompson’s new model of an atom described as?

-Plum pudding model


Briefly describe JJ Thompson’s plum pudding model

-Positively charged sphere with negative electrons embedded


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