Stoichiometry: 1.1- Intro to particulate nature of matter & chemical change

Question 1

Stoichiometry

Answer 1

from 2 Greek words. Stoicheion for element and metron for measure. Describes the relationships between the amount of reactants and products during chemical reactions. Form of book-keeping at the atomic level.

Question 2

Chemical Equations

Answer 2

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side
P(4)O(10)+H(2)O–>H(3)PO(4)

Question 3

Mole

Answer 3

The mass of substance containing the same number of fundamental units as there are atoms in exactly 12.000g of (12)C.

Question 4

Chemical Elements

Answer 4

Any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter.

Question 5

Native state

Answer 5

Refers to the occurrence of an element in an uncombined or free state in nature

Question 6

Chemical Compounds

Answer 6

Something that is composed of two or more separate elements; a mixture

Question 7

Chemical Change

Answer 7

Any change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking bonds between atoms. These changes are chemical: iron rusting (iron oxide forms), gasoline burning (water vapour and carbon dioxide form)

Question 8

Reactants

Answer 8

A substance that takes part in and undergoes change during a reaction

Question 9

Products

Answer 9

A substance that is formed as the result of a chemical reaction. Examples AgCl is the product of a reaction.

Question 10

Balancing the Equation

Answer 10

A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products. In other words, the mass and the charge are balanced on both sides of the reaction.

Question 11

Stoichiometric coefficients

Answer 11

In a balanced equation, both sides of the equation have the same number of elements. The stoichiometric coefficient is the number written in front of atoms, ion and molecules in a chemical reaction to balance the number of each element on both the reactant and product sides of the equation

Question 12

Mixture

Answer 12

A material system made up of two or more different substances which are mixed but are not combined chemically. Refers to the physical combination of two or more substances on which the identities are retained and are mixed in the form of solution, suspensions, and colloids.

Question 13

Homogeneous mixture

Answer 13

A mixture which has uniform composition and properties throughout. Ex- air is a homogeneous mixture of gases

Question 14

Heterogeneous mixture

Answer 14

A mixture is a combination of two or more pure substances in which the original substances retain their chemical properties. In some mixtures, the initial substances cannot be detected after they have been mixed

Question 15

States of matter

Answer 15

One of the distinct forms that matter takes on. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma

Question 16

Kinetic Theory

Answer 16

A fundamental theory of matter that explains physical properties in terms of the motion of atoms and molecules. Properties such as pressure an temperature are viewed as statistical properties of overall behaviour of large numbers of particles

Question 17

Inter-particle forces

Answer 17

Forces of attraction of repulsion which act between neighbouring particles (atoms, molecules, or ions) They are weak compared to the intramolecular forces, the forces which keep a molecule together

Question 18

Fluids

Answer 18

Any substance that flows or deforms under an applied shear stress. Fluids comprise a subset of the states of matter and include liquids, gases, and plasma. Ex- all liquids and gases are fluids (air, water, oil)

Question 19

Diffusion

Answer 19

The process of a substance spreading out to evenly fill its container or environment. In a solution, a concentrated solute diffuses to spread evenly in its solvent. In air, gas molecules diffuse to mix thoroughly. Substances diffuse from areas of high concentration to low concentration

Question 20

State symbols

Answer 20

In brackets show the physical state of the substance at the reaction temperature. Solid, liquid, gas, or dissolved in water.