Chapter 2 chemistry Flashcards
What is an element?
Any substance that cannot be broken down to any other substance by chemical reaction.
What are the four elements that make up 96% of living matter?
carbon, hydrogen, nitrogen, oxygen
What are trace elements?
Elements that are required by organisms in only minute quantities.
What compound accounts for the high percentage of oxygen in the human body?
Carbon dioxide (CO2)
What is matter?
Anything that takes up space and has mass
What is a compound?
A substance consisting of 2 or more different elements combined in a fixed ratio
What are essential elements?
Chemical elements required for organisms to survive, grow, and reproduce
What is the atomic nucleus?
An atom’s central core containing subatomic particles protons and neutrons
What is Dalton?
A measure of mass for atoms and subatomic particles
What is the atomic number?
The number of protons in the nucleus
what is mass number?
The total number of protons and neutrons
What is atomic mass?
The average mass of all isotopes of an element
What are isotopes?
One of several atomic forms of an element
What differs between isotopes of an element?
Number of neutrons
What is a radioactive isotope?
An isotope that is unstable, the nucleus decays spontaneously
What is Half-life?
The amount of time it takes for 50% of a sample of a radioactive isotope to decay
What is radiometric dating?
A method for figuring out the absolute age of rocks and fossils, based on the half-life of radioactive isotopes.
What is energy?
The capacity to cause change
What is potential energy?
The energy that matter possesses because of its location or structure
What are electron shells?
Energy level of electrons with different distances from the nucleus of an atom
What are valence electrons?
electrons in the outermost shell involved in the chemical reactions of an atom
What is the valence shell?
The outermost shell of an atom
what is an orbital?
The 3-dimensional space where an electron is found 90% of the time
What are chemical bonds?
An attraction between 2 atoms from sharing valence electrons or the presence of opposite charged on the atoms
What is a covalent bond?
A type of strong chemical bond in which 2 atoms share valence electrons
what is a molecule?
2 or more atoms held together by covalent bonds
what is a single bond
a single covalent bond, the sharing of one pair of valence electrons
what is a double bond?
A double covalent bond, sharing of 2 pairs of valence electrons
What is the valence?
the bonding capacity of a given atom
what is electronegativity?
The attraction of a given atom for the electrons of a covalent bond
Nonpolar covalent bonds
A type of covalent bond where electrons are shared equally between 2 atoms of similar electronegativity
polar covalent bonds
A type of covalent bond where electronegative differs
Ions
an stop or group of atoms that has gained or lost one or more electrons thus acquiring a charge
cation
a positively charged ion
Anion
A negatively charged ion
ionic bond
a chemical bond caused by the attraction between oppositely charged ions
ionic compounds/salts
A compound caused by the formation of an ionic bond
chemical reactions
the making and breaking of chemical bonds leading to changes in the composition of matter
