Chapter 2 - The Chemistry of Life Flashcards
What is matter?
Anything that takes up space and has mass. Matter is composed of elements.
What are the properties of water?
1) Water molecules like to “stick” together.
2) Water can moderate temperature.
3) Ice is less dense than liquid water.
4) Water is an excellent solvent.
What is an element?
A substance that cannot be broken down to other substances by chemical reactions. In other words, an element is composed of a single type of atom.
What is an atom?
The smallest unit of matter having the physical and chemical properties of an element.
What percentage of cells is made up of water?
70-95%
96% of living matter is made up what 4 essential elements?
Carbon, hydrogen, oxygen and nitrogen.
What is a compound?
Two or more elements combined in a fixed ratio.
What is an isotope?
Atoms of an element that have the same number of protons, but a different mass number.
Isotopes are considered stable if ______?
Their nuclei do not have a tendency to lose particles.
Are radioactive isotopes stable or unstable?
Unstable - nucleus decays spontaneously, giving off particles and energy.
What is the distance of an electron from the nucleus determined by?
It’s energy level
What is energy?
Capacity to cause change - ability to do work.
The farther an electron is away from the nucleus, the _____ potential energy it has.
More.
What is potential energy?
Store energy that matter possessed because of its position or location.
Electrons in the first shell closest to the nucleus have the _____ potential energy and electrons in the third shell have the _____ energy.
Lowest/most
An electron can move from one shell to another only if what?
The energy it gains or loses is exactly equal to the difference in energy between energy levels of the two shells.
What is electron configuration responsible for?
The chemical behavior of an atom. The number of electrons in the outer most shell is the most important factor in determining the chemical properties of an atom.
What does the chemical properties of an atom misrule depend on?
Number of valence electrons.
Atoms with same number of valence electrons exhibit similar chemical behavior.
What changes as you move left to right in a row of the periodic table?
Reactivity increases as you go up and right.
What elements are chemically unreactive?
Inert gases or noble gases with complete valence shells: He, Ar, Kr, Xe, Rn.