Chapter Two - The Chemical Contex Of Life Flashcards
What is an element?
A substance that cannot be broken down to on other substance by chemical reaction.
Organisms are composed of what?
Matter
What is a compound?
A substance consisting of two or more elements in a fixed ratio
What is matter?
Anything that TAKES UP SPACE and has MASS.
What is an atom?
Smallest unit of matter that still retains the properties of an element.
Atoms are composed of what?
Subatomic particles.
Name the three relevant subatomic particles and their charge.
- Neutrons (no electrical charge)
- Protons (positive charge)
- Electrons (negative charge)
What are the mass of both neutrons and protons measured in?
Daltons
What is an element’s atomic number?
The number of protons in the nucleus.
What is an element’s mass number?
The sum of protons plus neutrons in the nucleus.
What is the atomic mass?
An atom’s total mass.
What is an isotope?
Two atoms of an element that differ in the number of neutrons
Name two types of isotopes.
- Stable
* Radioactive
Explain the difference between a stable isotope and a radioactive isotope.
STABLE ISOTOPES are stable, while RADIOACTIVE ISOTOPES decay spontaneously, giving off particles and energy.
What is energy?
The capacity to cause change.
What is potential energy?
The energy that matter had because of its location or structure.
What is an electron shell?
An electrons state of potential energy or energy level.
What is the chemical behavior of an atom determined by?
The distribution of electrons in electronic shells.
What are Valence Electrons (valence shell)?
Electrons in the outermost shell.
What causes an element to become chemically inert?
A full valence shell.
Why are valence electrons important in an atom.
They determine the chemical behavior. (mostly)
What is an ORBITAL?
The three dimensional space where an electron is found 90% of the time.
What is a COVALENT BOND?
The sharing of of a pair of valence electrons by two atoms.
*In a covalent bond, the shared electrons count as part of each atom’s valence shell.
What is a molecule?
Two or more atoms held together by covalent bonds.
