Answer:
Atoms are composed of a central nucleus which is surrounded by orbiting <u>Electrons</u>.
Explanation:
The word Atom is derived from atomos meaning indivisible particle. An atom is a very small sized particle and its size is approximately 100 picometers.
Atoms are composed of a Nucleus which contains protons and neutrons and the nucleus is surrounded by orbiting electrons. Also, the nucleus is positively charged due to +ve protons and the electrons revolving around nucleus are -vely charged making overall atom neutral in nature.
Atoms react with another atoms due to the presence of valence electrons present in the valence shell of an atom. The valence electrons would make a covalent bond by mutually sharing the electrons or it may form an ionic bond by gaining and loosing valence electron.
The molarity of a solution if it tale 12.0 grams of Ca(No3)2 is calculated as below
molarity = moles/volume in liters
moles = mass/molar mass = 12.0 g/ 164 g/mol = 0.073 moles
molarity is therefore = 0.073/0.105 = 0.7 M
Answer:
Valence electrons are involved in Reaction B but not in Reaction A.
Explanation:
The description of reaction A in which protons are lost or gained by the atom of the element is a nuclear reaction. In nuclear reactions, the nucleons which are the protons and neutrons drives the reaction. No valence electrons in the orbiting shells are involved in this kind of reaction. During this type of reaction, an atom changes it identity to that of another.
Reaction B in which no identity change occurs is a chemical reaction. In chemical reactions bonds are formed by the atoms using the valence electrons that orbits round the central nucleus. The atoms remain the same but it chose to attain stability and an inert configuration by losing or gaining electrons.
