Ch#1 : Fundamentals Of Chemistry Flashcards
Learn about the branches of chemistry , moles and basic definitions used in chemistry. (8 cards)
Define matter , substance , element and compound.
Matter : Anything that occupies space and has mass is called matter.
Substance : Any matter that has a particular characters which differ from the characteristics of another type of matter.
Element : A substance which cant be converted into simpler substances.
Alt Def:A substance whose atoms have the same atomic no.
Compound : A pure substance that consists of 2 or more elements held in fixed proportions by natural forces called chemical bonds. Their properties differ from the elements from which they are formed.
What is a mixture? , Define the 2 types of mixture. Give examples
Mixture : An impure substance that contains two or more pure substances that retain their individual chemical characteristics.
A mixture can be converted into 2 or more pure substances by a physical method.Example : Air
- A mixture that consists of two or more visibility different components is called a Heterogeneous Mixture. Salt + Sand
- A mixture that consists of only one phase is called a Homogeneous Mixture. Salt + Water
What is atomic number and mass number?
Atomic No: The number of protons in the nucleus of an atom.
Mass number : The sum of electrons and neutrons in an atom.
What is relative atomic mass and amu?
The first quantutative info about atomic masses came from the work of Dalton, Gay Lussac , Lavioser , Avogadro and Berzelius. By observing the proportions in which elements combine to form various compounds , 19th century chemists calculated relative atomic masses. An atom is a extremely small particle so we cant measure its mass. We can determine the mass of one atom of an element relative to another experimentally. This is done by assigining a value to the mass of one atom of a given element so it can be used as a standard. By international agreement in 1961. Light isotope carbon c-12 has been chosen as a standard. This value has been determined accurately with a mass spectrometer. The mass of all elements is compared to the mass of carbon c-12.
Definition : The mass of an aton relative to the mass of a c12 atom is called relative atomic mass.
Mass of 1 C-12 atom = 12amu.
1amu = mass of 1 C-12 atom/12
What are empirical and molecular formulas?
Empirical Formula : The chemical formula which gives the simplest whole number ratio of atoms of each element.
Molecular Formula: The chemical formula which gives the actual whole number ratio of atoms of each element.
Define Molecular and formula mass
Molecular mass is the sum of atomic masses of all atoms present in a molecule.
Formula mass is the sum of atomic masses of all the atoms in the formula unit of a substance.
What is a mole? Define molar mass.
A mole is the amount of a substance which contains 6.022 *10^23 particles of that substance. This experimentally determined number is called Avogadro’s number. Represented by Na.
Molar mass : The mass of one mole of a substance.
An atom is an electrically neutral particle? Why?
An electron carries a negative charge -1.662 x 10^-19 C(coulomb) and a proton has a positive charge +1.662 x 10^-19C.Because the number of electrons and protons is equal in an atom , the opposing charges cancel each other out. This results in atoms being electrically neutral.
