Chap 3 questions Flashcards
State Law of conservation of mass
Law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. The mass on the reactants and products side are always same.
State Law of constant proportions with example
The law of constant proportions states that chemical compounds are made up of elements that are present in a fixed ratio by mass. For example, H20 has hydrogen and oxygen. The ratio of mass of the elements is 1:8
Mention the 6 pointers in Dalton’s atomic theory
1) All matter is made up of very tiny particles called atoms, which participate in chemical reactions
2) Atoms are indivisible particles, which cannot be created nor destroyed in a chemical reaction
3) Atoms of a given element are identical in mass and chemical properties
4) Atoms of different elements have different masses and chemical properties
5)Atoms combiene in the ratio of samll whole numbers to form compounds
6) The relative number and kinds of atoms are constant in a given compound
What is an atom?
Atom is the building block of all matter. They are very small. Way smaller than we can imagine. Atomic radius is meassured in nanometers 10-9m.
Define relative atomic mass and mention how it is calculated
We use relative atomic mass to determine the mass of an atom. The value of relative atomic mass is 1/12th of carbon-12 isotope. The reason it was chosen is because using carbon-12 as the standard reference, we mostly get whole numbers for mass of other elements
What is a molecule
A molecule is in general a group of two or more atoms that are chemically bonded together, that is tightly held together by attractive forces. A molecule can be defined as the smallest particle that is capable of an independent existence.
Explain molecule of elements
Molecules of elements are basically molecules that are formed by the same element. For example O2 O3 H3 etc.
Define atomicity
The number of atoms constituting a molecule is known as its atomicity. For example the atomicity of O2 is 2
What is an ion
An ion is a positively or negatively charged particle. Ions may consist of a single charged atom or a group of atoms that have a net charge on them. A positively charged ion is called cation and negatively charged ion is called anion
Mention the 3 rules for writing chemical formula
1) The valencies or charges on the ion must balance
2) Metal is always written first
3) In compounds formed with polyatomic ions example NaOH. If there are two or more ions of polyatomic then use brackets. So write Na(OH)2
