Atomic structure and isotopes - 2.1 - (1) Flashcards
Page 8 & 9
What does the atom consist of?
a nucleus made up of two types of subatomic particles = protons and neutrons
What is the third type of subatomic particle?
an electron which occupies a region outside the nucleus
How are electrons arranged?
around the nucleus in shells
What kind of masses do atoms and their subatomic particles have?
tiny masses
What do chemists use instead of working in grams?
they compare the masses of subatomic particles using relative masses
What virtually has the same mass as a neutron?
proton
What is the negligible mass of an electron?
1/1836th the mass of a proton
What do accurate measurements show?
a neutron has a slightly greater mass than a proton
By which factor is a neutron slightly greater than a proton?
1.001375
What do chemists assume after they see that neutrons have a slightly greater mass than protons by the factor suggested?
this is close to 1 that chemists usually assume that protons and neutrons have the same mass
What type of subatomic particle has a positive charge?
proton
What type of subatomic particle has a negative charge?
electron
The charge on a proton…
is equal but opposite to the charge on an electron - the charges balance
What type of subatomic particle has no charge?
neutron
What is the actual charge on a single proton that is tiny?
+1.60217733 x 10^-19C
What is a much easier way instead of using actual charges?
relative charges
What is the relative charge for a proton?
1+
What is the relative charge for an electron?
1-
Nearly all of an atom’s…
mass is in the nucleus
What do atoms contain the same number of?
protons and electrons
What is cancelled by the total negative charge from electrons?
the total positive charge from protons
What is the overall charge of an atom?
zero
Is an atom neutral?
yes
What are neutrons thought to be as for the nucleus?
as a glue that holds the nucleus together despite the electrostatic repulsion between its positively charged protons
Most atoms contain the same number of, or slightly more,…
neutrons than protons
What is needed as the nucleus gets larger?
more and more neutrons
What identfies an element?
the number of protons in an atom
As of 2014, the existence of how many elements has been confirmed?
114 elements
Every atom of the…
same element contains the same number of protons
Different elements contain atoms…
that have different numbers of protons
The periodic table lists elements in order of the…
number of protons in the nucleus
Each element is shown with the number of…
protons as its atomic number (or number of protons)
