These are 11 questions each with its jusitified answer:
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1. Compounds have the same properties as the elements that form them.
A.True
B.FalseAnswer: False
Justification:
The properties of compounds although due to the elements and the bonds formed between them have unique properties, different to those of the elements.
That is a feature of the chemical reactions: the formation of one or more new compounds from elements are critically influenced by the bonds.
For example, think about the compound NaCl (table salt) you can see that their properties are way different from the elements Na (sodium) and Cl (chlorine) being the former highly reactive with water and the latter a strong posion. You cannot eat either Na or Cl, but certainly you can eat NaCl.
2.Electrons on the outermost layer of an atom are called valence electrons.
A.True
B.FalseAnwer: TRUE.
Justification:
The valence electrons are those that participate in the formation of chemical bonds and the electrons of the outermost shell are closer to interact with other atoms and so form chemical bonds.
</span><span>For a main group element, i.e. groups 1, 2, 13, 14,15, 16, 17, and 18, a valence electron can exist only in the outermost electron shell; in a transition metal, those of the groups 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12, a valence electron can also be in an inner shell
3) Compounds formed by sharing electrons are called _____ compounds.
A.) Ionic
B.) covalent
C.) positive
D.) negative
E.) neutralAnswer: option B.) covalent.
Justification:
</span><span><span>The covalent bond is formed bu sharing a pair of electrons between atoms
in a molecule.
Sharing electrons means that the atoms neither gains or loses an electron, hence no ions are
formed.
The number of covalent bonds an atom can form depends upon the
number of electrons that it has available for sharing.</span>
4) Compounds formed by transferring electrons are called _____ compounds
A.) Ionic
B.) covalent
C.) positive
D.) negative
E.) neutralAnswer: option A. ionice.
Justification:
Transference of electrons means that one atom loses electrons while other atom gains electrons.
Losing and gaining electrons cause the formation of ions, which are electrically charged particles. The elecrostatic attraction between positive ions and negative ions drives to the formation of ionic compounds.
5) Elements that lose electrons will have a _____ charge.
A.) Ionic
B.) covalent
C.) positive
D.) negative
E.) neutralAnswer: option C. positive.
Justification:
Atoms are electrically neutral because they have the same number of protons (positive particles) as electrons (negative particles).
When a neutral atom loses an electron (negative particle) it will stay with more protons than electrons and leading to a net positive charge.
6) Elements that gain electrons will have a _____ charge
A.) Ionic
B.) covalent
C.) positive
D.) negative
E.) neutralAnswer: option D.) negative.
Justification:
A neutral atom has the same number of electrons as protons. Electrons are negative particles, so if an atom gains electrons it will end having more negative particles (electrons) than positive (protons) resulting in a negatively charged particle.
7) Hydrogen, an element, and Oxygen, an element, are flammable in element form.
True
FalseAnswer: False.
Justification.
Hydrogen is flammable but oxygen is not flammable.
Flammable is a substance that burns.
Indeed hydrogen gas (the diatomic molecule) burns easily in air, while oxygen being an oxidizer does not burn but causes other substances to oxidize, which include combustion.
8) Elements can share electrons or transfer them to another element
True
FalseAnswer: true.
Justification:
It is the mutual interaction between two elements which lends to the final sharing or transference of electrons. So, while Cl for example, form a ionic compound with Na (meaning that Na transferes one electron to Cl and form ions), the same Cl shares electrons with O to form covalent compounds.
9.Ionic bonds happen when electrons are given up by one atom to another
True
FalseAnswer: True
Justification:
When an atom gives up an electron if forms a positive ion (called cation), and when the other atoms receives the electron if forms a negative ion (called anion).
The two charged ions (cation and anion) are electrostatically attracted forming the ionic compound.
Since the number of characters exceeded the limit of 5000 characters the answers to questions 10 and 11 are in the pdf file attached.</span>
