Q11. What are the lanthanides?
Ans. The lanthanides are a group of 15 elements in the middle of the periodic table that take their name from lanthanum. They are all shiny silvery metals and often occur naturally together. They all have two electrons in their outer electron shells. This makes them chemically similar- they are all very reactive.
Q10. Who discovered radium?
Ans. The Polish-French physicist Marie Curie(1867-1934), born Marya Sklodowska, is the only woman to have won two Nobel prizes- one in 1903 for her part in the discovery of radioactivity, and one in 1911 for her discovery of the elements polonium and radium.
Q9. Why is carbon so special?
Ans. Carbon is the most friendly element in the Universe. With four electrons in the outer shell of its atom (and so four gaps), carbon atoms link very readily with other atoms.
Q1. What is the periodic table?
Ans. All the elements can be ordered according to their properties, forming a chart called the periodic table. Columns are called groups, rows are called periods. Elements in the same group have the same number of electrons in the outer shell of their atoms and similar properties.
Q7. What is a metal?
Ans. Most people can recognize a metal. It is hard, dense and shiny and goes ‘ping’ when you strike it with something else made of metal. It also conducts both electricity and heat well. Chemists define a metal as an electropositive element, which basically means that metals easily lose negatively charged electrons. It is these lost,’ free’ electrons that makes metals such excellent conductors of electricity.
Q6. What are the transition metals?
Ans. Transition metals are the metals in the middle of the periodic table, such as chromium, gold and copper. They are generally shiny and tough, but easily shaped. They conduct electricity well and have high melting and boiling points.
Q5. What is the heaviest element?
Ans. The heaviest is hahnium. It has 105 protons and 157 neutrons in its nucleus. The atomic mass of hahnium is 262.
Q4. Why are some elements reactive?
Ans. Elements are reactive if they readily gain or lose electrons. Elements on the left of the periodic table, called metals, lose electrons very easily- the further left they are, the more reactive they are. So Group 1 metals (called the alkali metals) including sodium, potassium and francium are very reactive.
Q3. What are noble gases?
Ans. Group 0 is the furthest right-hand column of the periodic table. This group is called the noble gases, because they have full-up outer electron shells and so nobly stay aloof from any reaction with ‘base’ metals or any other substance. They are sometimes called inert gases.
Q2. How many elements are there?
Ans. New elements are discovered every so often, but the total number identified so far is 112.