Atoms Flashcards
What are atoms?
The smallest unit of a pure substance.
It makes up ‘matter’.
What is the structure of atoms?
Sub-atomic particles: protons, neutrons, electrons and space
What is the electrical charge, mass and position of the proton?
Positive charge, 1840x electron mass ( = neutron mass), inside nucleus
What is the electrical charge, mass and position of the neutron?
No (neutral) charge, 1840x electron mass ( = proton mass), inside nucleus
What is the electrical charge, mass and position of the electron?
Negative charge, 1x electron mass ( = neutron mass), shells
What is the centre of an atom called and what sub-atomic particles are present?
Protons and neutrons make up the nucleus.
Where is the mass of an atom concentrated and why?
In the nucleus because protons and neutrons have a heavier mass than electrons.
What is the charge of an atom and why?
The overall charge of an atom is zero (electrically neutral) because there is a balance between positive and negative charges, meaning they have the same number of protons and electrons.
What is most of an atom’s volume made up of?
Empty space.
What is the overall charge of the nucleus?
Positive - protons have a positive charge and neutrons have no charge.
What is an element?
Pure substance made of one kind of atom.
What is a compound?
Chemically combined atoms of two or more elements.
What is a mixture?
Two or more substances not chemically combined.
Atomic number = ?
The number of protons.
Different number of protons =
Different elements formed.
Protons + neutrons = ?
Mass number
Mass number - atomic number = ?
Number of neutrons
Number of electrons = ?
Number of protons (atomic number)
What is the notation of atoms?
Nuclear symbol form - atomic mass/weight, atomic number, atomic symbol.
What are electrons arranged into and how many can go into each?
Shells or energy levels.
1st = 2
2nd = 8
3rd = 8
Can electrons be lost or gained?
Yes, electrons on the valence (outer) shell can be transferred to another atom.
What happens when electrons are lost or gained and what is the result of it?
There is an imbalance of positive and negative charges. This results in an overall positively or negatively charged particle.
What is an ion and what is the name of the formation of ions?
An atom or particle with a net charge; charged atoms. The process is called ionisation.
When does ionisation occur?
When atoms form chemical bonds or are exposed to radiation.
Why do ions normally have a full outer shell of electrons?
It is a stable arrangement.
What is the difference between metal and non-metal ions?
Metal ions lose electrons while non-metal ions gain electrons.
What do the names of negative ions usually end with?
“ide”. e.g. when oxygen becomes a negative ion its name changes to oxide.
How is an ion written?
Element symbol followed by overall charge in subscript. e.g. if oxygen gains 2 electrons, it has a charge of -2. the name and formula of the ion is oxide (O^2-)
Why can current flow through water?
Water contains ions of dissolved salts and metals which freely move throughout the fluid.
Negative ions form when an atom _______ electrons and positive ions form when an atom ________ electrons.
gains, loses
What is static electricity?
When you rub two objects together, there is a temporary transfer of electrons which causes an imbalance of electrical charges.
What is the relationship between positive and negative charges?
Opposite charges attract, like charges repel.
What are isotopes?
Isotopes of an element have the same number of protons but different number of neutrons, meaning it has a different mass number. They have the same chemical properties.
Which one is more unstable: heavier or lighter isotopes?
Heavier isotopes tend to break down into smaller atoms because they are more unstable.
True or False?: Most elements exist as a mixture of isotopes.
True
For isotopes, mass number is __________ while atomic number is the _________
Different, same
What is a molecule?
Two or more atoms connected by chemical bonds.
The smallest division of a compound.
What is a positive and negative ion called?
Cations and anions.
Electron cloud model vs. planetary model
Model of an atom in which electrons move freely.
Model of an atom in which electrons move in defined orbits.
