The Chemicals of Life Flashcards
ATOMS & ELEMENTS
What is an element ?
Element is a substance that cannot be split into simpler substances by chemical means.
How many elements created all parts of the Earth ?
92 naturally occurring elements.
How many elements are important for living organisms?
Only 21 out of 92.
Name the most common elements.
1- carbon(C)
2-oxygen(O)
3-hydrogen(H)
4-nitrogen(N)
What is the smallest possible amount of any element called?
Atom
Give the definition of molecules.
Molecules are formed when two or more atoms join together. These atoms can be of the same element or different elements.
Define compounds.
The combination of different elements.
Explain the structure of the atom.
The main mass of each atom is in a central nucleus.
The nucleus is made of even smaller particles called protons & neutrons.
Are there any electrons in the atom?
Electrons are minute particles. They move around the nucleus at very high speed within electron shells or energy levels. Their mass is negligible compared with that of the neutron or proton.
Explain the different electrical properties that the components of an atom have.
-Neutrons have no electrical charge.
-Electrons have a negative charge.
-Protons have a positive charge.
Extra Note: An atom with with an equal number of electrons and protons has no overall electrical charge.
Which element’s atoms are considered an exemption ?
Hydrogen atoms because they have one proton in the nucleus but no neutrons.
Define ions.
Ions are atoms that have gained an electrical charge.
Explain how atoms can become negatively and positively charged.
+ when some atoms loose one or more electrons.
-when some atoms gain one or more electrons.
What is an atomic number?
The number of protons in the nucleus of an element.
Extra Note: In a neutral atom the number of protons equals the number of electrons.
Define isotopes.
Atoms of any particular element always have the same number of protons but the number of neutrons can vary. These different versions of the same element we call them isotopes. Isotopes are identified by the mass number of the atom which is the number of protons + the number of neutrons. Different isotopes of the same element have different mass numbers BUT the same atomic number.
Explain how some isotopes are radioactive?
Radioactive means that they are unstable. they change spontaneously to form a different isotope of the same element or to a completely different element. Therefore radiation in given during this change.
