Chapter 2: Chemical Basis Of Life Flashcards
(43 cards)
What is matter?
Anything that occupies space and has mass. It is found in 3 physical states: solid, liquid, and gas.
What is an element?
A substance that cannot be broken down to other substances by chemical means.
What is a compound?
A substance consisting of two or more different elements combined in a fixed ratio. EX: table salt (NaCl), consists of one atom of the element sodium (Na) for every atom of chlorine (Cl).
What is trace elements?
An element that is essential for life but required in extremely minute amounts. Present in minute quantities.
What is an atom?
Named from a Greek word meaning “indivisible”. It is the smallest unit of matter that still retains the properties of an element.
What is a proton?
A subatomic particle with a single positive electrical charge (+).
What is an electron?
A subatomic particle with a single negative charge (-).
What is a neutron?
A subatomic particle having no electrical charge. Found in the nucleus of an atom.
What is a nucleus?
An atom’s central core, containing protons and neutrons. The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin.
What is Atomic number?
The number of protons in each atom of a particular element. EX: an atom of helium with 2 protons has an atomic number of 2.
What is mass number?
The sum of the number of protons and neutrons in its nucleus. EX: helium the mass number is 4. The mass of a proton and the mass of a neutron are almost identical and are expressed in a unit of measurement Called the dalton.
What is Atomic mass?
The atomic mass is approximately equal to it’s mass number. The sum of its protons and neutrons- in daltons
What is an isotope?
One of several atomic forms of an element, each with the same number of protons but a different number of neutrons.
An element has the same number or protons and behave identically in chemical reactions, but they have different numbers of neutrons.
What is a radioactive isotope?
An isotope whose nucleus decays spontaneously, giving off particles and energy.
What is an electron shell?
A level of electrons at a characteristic average distance from the nucleus of an atom.
What is a chemical bond?
An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.
What is an ionic bond?
A chemical bond resulting from the attraction between oppositely changed ions.
What is a covalent bond?
A type of strong chemical bond n which two atoms share one or more pairs of valence electrons. Atoms do not transfer electrons but actually share electrons between them.
What is a molecule?
Two or more atoms held together by covalent bonds.
What is electronegativity?
The attraction of a given atom for the electrons of a covalent bond.
What is a non polar covalent bonds?
A type of covalent bond n which electrons are shared equally between two atoms of similar electronegativity.
What is a polar covalent bond?
A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.
What is a hydrogen bond?
A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule (or in another region of the same molecule.)
What is a polar molecule?
A molecule containing polar covalent bonds and having an unequal distribution of charges in different regions of the molecule.
