Question

VII. Define positive feedback VIII. Given the symbol of an element from the periodic table a. Describe the distribution of protons, neutrons and electrons in the atom, including the distribution of electrons in the shells. b. Describe the relative stability of electron shells given the number of electrons in that shell c. Define isotope and calculate the atomic mass of a given isotope d. Determine the atomic mass of the atom IX. Define “anion” and “cation” X. Define the types of chemical bonds (covalent, ionic, hydrogen) and describe their features a. Define polar bond b. Describe the situation in which hydrogen bonds will form XI. Define “solute” and “solvent” XII. Determine the difference in acidity/alkalinity of two points on the pH scale

Answer 1

VII ) positive feedback is a process in which end products of an action causes more of that action to occur in feedback loop.it amplifies the original action.

Ex.blood clotting: when a blood clots the platelets get actibated which in turn more platelets thereby enlarging the clot.

VIII) MORE INFO NEEDED: the periodic table

IX) anion- a negatively charged ion is called anion.it attracts the anode part of an electrode during electrolysis.

Cation- it is a positively charged ion. It attracts the cathode part of an electrode during electrolysis.

X) COVALENT BOND:is also called a molecular bond.a chemical bond that involves of electron pairs between atom.

Ex.METHANE (CH4)

Features:low melting point and boiling point.

-most exists as gas or vaporize quickly at room temporature

-do not conduct electricity in water

IONIC BOND:formed by electrostatic forces of attraction between oppositely charged ions.

Ex. Table salt..NaCl

Features:- crystalline structure

-high melting point and boiling point

-excellent electric conductors

-generally soluble in water

HYDROGEN BOND:weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.

Ex.water. H2O

features:intra molecular bonds

-formed between different atom of 2 molecules

-high boiling point and melting point than ionic bond.

a) POLAR BOND:A polar bond is a covalent bondbetween two atoms where the electrons forming the bond are unequally distributed. This causes the molecule to have a slight electrical dipole moment where one end is slightly positive and the other is slightly negative.

b) situations where hydrogen bond is formed:

- if one is covalent bond and other is hydrogen bond-ex. Hydrogen fluoride

-can be formed in water.

XI) SOLUTE:solute is a substance that is dissolved in another substance ( solvent)

SOLVENT:it is a substance in which solute is dissolved.

Ex. Salt is dissolved in water

Salt- solute

Water-solvent.

XII)ph 1-6-acidic.

Ph 7-neutral

8-14-alkaline

As the ph increases-basicity increases

As ph decreases -acidity increases( image taken from shutterstock)