CHEM 120 PROFESSIONAL SCIENCE PREP QUESTIONS AND ACCURATE ANSWERS GRADED A+

CHEM 120 PROFESSIONAL SCIENCE PREP
QUESTIONS AND ACCURATE ANSWERS
GRADED A+

●● Significant Figure Rules
Answer: 1. All non-zero digits are always significant
2. Zeroes between non-zero digits are always significant
3. Zeroes to left of first non-zero digit (either before or after decimal
point) are never significant
4. Zeroes to the right of last non-zero digit
a. after decimal point are always significant
b. which are before decimal point are not significant


●● conversion factor
Answer: relationship between two quantities expressed as a fraction


●● dimensional analysis
Answer: conversion of a measurement in one unit into another by the
use of conversion factors


●● True

,Answer: T/F: number of protons never changes according to periodic
table


●● number of protons
Answer: atomic number=_______________________


●● number of neutrons
Answer: mass number=_______________________


●● isotopes
Answer: atoms with same number of protons (same electron) but
different number of neutrons


●● atomic mass
Answer: weighted average of the isotopic masses of all stable isotopes of
an element


●● compound
Answer: substance composed of 2+ elements that are chemically
combined


●● molecular compound
Answer: compound in which atoms are held together by covalent bonds

, ●● ionic bond
Answer: nonmetal and metal (giving away of electrons by one and
receiving by the other); electrostatic interactions between positive and
negative ions


●● covalent bond
Answer: 2 nonmetals (sharing of bonds); the sharing of electrons
between two atoms


●● ion
Answer: atom that has an electrostatic charge


●● cation
Answer: positively charged atom


●● anion
Answer: negatively charged atom


●● formula unit
Answer: simplest whole number ratio of ions in ionic compound


●● polyatomic ion