atoms and isotopes Flashcards
Where is most mass of an atom concentrated
in the nucleus
describe the arrangement of protons,neutrons and electrons in an atom
-the protons and neutrons are found in the atoms nucleus
-the electrons are found in distinct energy levels around the nucleus
what type of charge does the nucleus of an atom have?why?
-positive charge
-The nucleus contains protons and neutrons:protons have positive charge, neutrons have no charge
Give 2 ways an atom’s electron arrangement can be changed
- Absorbing electromagnetic radiation
- Emitting electromagnetic radiation
Explain how an atoms electron arrangement changes when it absorbs electromagnetic radiation
-Electrons move further away from the nucleus
-They move to a higher energy level
Explain how an atom’s electron arrangement changes when it emits EM radiation
-Electrons move closer to the nucleus
-They move to a lower energy level
How does the ratio of protons to electrons in an atom result in it having no overall charge
-Number of protons=number of electrons
-Protons and electrons have equal and opposite charges ,so charge cancels
What do all forms of the same element have in common
They all have same number of protons
What is the name given to number of protons in an atom
Atomic number
What is an atoms mass number
The total number of protons and neutrons
what is an isotope of an atom
An atom of an element that has a different number of neutrons but same number of protons
how do atoms turn into positive ions
-They lose one or more outer electrons
-Electrons are negatively charged,so the resultant charge of the atom is positive
What may lead to a scientific model being changed
The discovery of new experimental evidence which doesn’t agree with the existing theory
How did the plum-pudding model describe the atom
A ball of positive charge, with negatively charged electrons distributed evenly through it
What is the name given to the currently accepted model of the atom
The Bohr nuclear model
