The smallest unit of matter that can retain the properties of elements.
What are elements?
The smallest units of matter that can be derived by normal chemical means.
What is the relationship between atoms and temperature?
Temperature is in effect the imperceptible kinetic movement of atoms. The hotter a substance is, the more its atoms are moving and the colder it is, the less movement.
What are the 3 states of matter?
Solid: Matter with strong bonds, creating rigid shape and structure and little kinetic movement.
Liquid: Matter with flexible bonds, allowing more kinetic movement. They are incompressible but fill their container.
Gas: Free moving atoms with no bonds, they fill their container and can also be compressed.
What is the structure of atoms?
An incredibly small and dense nucleus composed of positively charge protons and neutral neutrons, orbited at a (relatively large) distance by negatively charged electrons which form shells.
What are protons?
Subatomic particles with a positive charge, found in the nucleus.
What are neutrons?
Particles found in the nucleus, comparable to protons but they carry no charge. Their presence is believed to be involved in the strong nuclear force.
What are electrons?
Negatively charged particles that orbit the nucleus at fantastic speeds, so fast as to create "shells." They are much smaller than their proton and neutron counterparts.
What do the protons of an element determine?
Protons determine the identity of the element; an element will have the same number of protons regardless of the presence of neutrons or electrons.
What is the atomic number of an element?
It refers to its identity and is equal to its number of protons.
What is the mass number of an element?
Atomic mass is found from the addition of the number of protons and neutrons. It is not equal to the atomic number because isotopes will have different numbers of neutrons.
What is an isotope?
An isotope is a variation of an element according to the number of neutrons present in an atom. Its named according its mass number e.g. Carbon 12, Carbon 13 and Carbon 14
How are electrons arranged around the nucleus?
Electrons orbit the nucleus and are arranged by the distance at which they orbit, their incredibly fast movement creating what is called a "shell."
What is atomic valency?
Valency refers to the number of electrons in the outermost (valence) shell of an electron. Atoms with 1 shell are most stable with a valency of 2, atoms (<20) with 2 shells or more are most stable with a valency of 8.
What is special about the noble gases?
Noble gases all have full valency. That is they all have 8 electrons in their valence shell and have maximum stability, except for helium which has only one shell and thus a valency of 2.
What is the octet rule?
The octet rule states that all atoms under the atomic number of 20 will try to achieve a valency of 8, except for those with one shell.
How can atoms attain a full valence shell?
By forming molecules. Through ionic or covalent bonding atoms can achieve stability.