Why do metals have a high boiling and melting point?
Because there is no ionic bonding between them
100
Non-metals have no metallic luster, and do not reflect
light. also non-metals exist in two of the three states of matter at room temperature: gases and solids. (True or false ?)
True
100
Name some examples of metalloids.(atleast 4)
They are boron,silicon,germanium,arsenic,antimony,tellurium,
polonium
100
What is another name for noble gases?
Inert gases
100
This English scientist noticed that properties of elements repeat with every eighth element. He attempted to arrange the elements using the octave as a basis in 1864. Who was he?
John Newlands
200
Why transition elements are called transition elements?
Transition elements are called transition elements because the electrons in these elements are not in process of filling valence(outermost ) shell
200
Name the three categories under non-metals.
Halogens, noble gases, and other non-metals
200
why are metalloids described as semi-conductors
Because the bonds break easily and they have free electrons to pass electricity.
200
Why are noble gases found as single atoms and not molecules?
Because they have fuller outer shells and do not need to
bond with other elements.
200
In spite of Mendeleev's version of the periodic table being accepted, it contained a fundamental flaw. Ordering the elements by atomic mass led to some elements being out of place. In 1913, an English chemist decided to order the elements by their atomic numbers. Who was this man?
Henry Moseley
300
Which metal is a liquid at room temperature?
Mercury
300
which non-metal helps in forming fluorescent light
fluorine
300
uses of metalloids?
Metalloids have various uses. Silicon is classified as a Metalloid and is used in computer chips.Boron is also a Metalloid and is used in making glass
300
Why do noble gases have low boiling points?
they are all gases at room temperature and have weak
intermolecular forces of attraction. Hence have low boiling point.
300
Who proposed the Law of Triads?
John Dobereiner
400
what is the difference between alkali metals and alkali earth metals?
Alkali metals are from group 1 and have single electron on outer shell.
Alkali earth metals are from group 2 and have two electrons on outer shell.
400
Why are non-metals poor conductors of electricity?
Non - metals have fewer free electrons. Electrons in Non-metals are held tightly, they are not allowed to move freely.
400
what property makes metalloids unique among other elements? give the example of silicon to explain
Metalloids exhibit characteristics of both classes. Silicon, for example, possesses a metallic luster, yet its an inefficient conductor and is brittle
400
Why can the electrons of the noble gases at the end of the group can be easily removed than the ones on top of the group?
because the noble gases at the end of the group are heavier and are held less firmly together by electromagnetic force than lighter noble gases, making it easier to remove outer electrons from heavy noble gases.
400
What did Mendeleev do because of which he came to be known as the father of Periodic Table?
Mendeleev is considered the father of the periodic table because he arranged the elements according to their properties and predicted the arrangement of elements which were not discovered yet.
500
why do only metals rust why not non-metals?
metals have extra electrons. which they give to water and oxygen. non-metals take electrons so rusting doesn't occur
500
Why do Non - metals accept electrons from metallic
elements so effectively during a reaction?
These elements wish to form an octet (8 valence electrons). They have more than 4 valence electrons and so they wish to gain electrons to fill the octet.
500
What is the function of Metalloids in computers?
silicon and germanium are two metalloid elements that are used to make computer chips.
500
Why do different noble gases give out unique colors when energy is passed into them?
This is because different noble gases have different
number of electrons.
500
What did the law of triads suggest?
it suggests that the middle element in the three elements had properties that were an average of the other two.