What is the significance of an electronegativity difference of 1.7 between 2 atoms?
O A. It tells which atoms form positive ions and which atoms form
negative ions.
OB. It represents the boundary between what is considered to be an
ionic or a covalent bond.
C. It determines if the 2 atoms will react to form a molecule.
D. It identifies which metal atoms will join together to form metallic
bonds
Am

B. It represents the boundary between what is considered to be an  ionic or a covalent bond.

Electronegativity is the ability of atoms to attract electrons, especially in covalent bonds (sharing of electron pairs)

In a periodic system, electronegativity increases in a group, from bottom to top, and in a period from left to right.

From this difference in electronegativity, we can determine the ionic compound, polar or non-polar

Pauling determined the electronegativity scale (based on bond energies), between 0.7 - 4 (Fluorine has the highest number of electronegativities: 4)

Polar covalent compounds have a large electronegativity difference, while nonpolar compounds have a small electronegativity difference.

We can use the difference in electronegativity between the 2 bonded atoms to determine their polarity

Example

H = 2.1

O = 3.5

H₂O = 3.5-2.1 = 1.4 >> polar

= 3.5-3.5 = 0 >> non polar

qualitative observation deals with data that can be observed with our senses: sight, smell, touch, taste, and hearing. they do not involve measurements or numbers. for instance, colors, shapes, and textures of objects are all qualitative observations.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.