practice questions

• the mass number of an element indicates the total number of neutrons and protons in a nucleus
• the empirical formula of the ionic compound of Cs and Cl react is CsCl
• anions result from the gain of electrons
• cations result from the loss of electrons
• cations have a positive charge
• anions have a negative charge
• the chemical formula of magnesium chloride is MgCl2
• sodium oxide chemical formula is Na2O
• iron (ii) sulfide chemical formula is FeS
• aluminum fluoride chemical formula is AlF3
• the ionic compound that forms aluminum and sulfur is Al2S3
• 0.0000033 in scientific notation is 3.3 x 10^-6
• 7800000 in scientific notation is 7.8 x 10^6
• 2112 in scientific notation is 2.112 x 10^3
• OF2 is oxygen difluoride
• the atomic nucleus in made of protons and neutrons
• the atomic number tells you the number of protons in the atom
• isotopes are elements with the same number of protons but different number of neutrons
• in a covalent compound nonmetals share electrons
• sodium is a metal and therefore is loses electrons when it forms an ion
• solids have the highest density
• non polar covalent bond c-H
• metals have the lowest electronegativity, they donate electrons to attain an octet
• the BF3 molecule is trigonal planar
• selenium forms an ion with a charge of -2
• in an ionic compound the metals donate electron to nonmetals
• oxygen forms an ion charge of -2