1) Answer is: Silicon is in the same group and also has 4 valence electrons.
Carbon is a chemical element with symbol C and atomic number 6, which means it has 6 protons and six electrons. Four valence electrons are in 2s and 2p orbitals.
Electron configuration of carbon atom: ₆C 1s² 2s² 2p².
Silicon (Si) is element with atomic number 14 (14 protons and 14 electrons).
Four valence electrons are in 3s and 3p orbitals.
Electron configuration of silicon atom: ₁₄Si 1s² 2s² 2p⁶ 3s² 3p².
2) Answer is: covalent bond.
When the electronegativity difference is greater, the bond polarity is increasing.
Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.
Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.
For example: Δχ(P-S) = 2.6 - 2.2 = 0.4; electronegativity difference between phosphorus and sulfur is 0.4, this bond is covalent.
3) Answer is: hydrogen has 1 valence electron.
Hydrogen (H) has atomic number 1, it means it has one proton and and one electron.
Electron configuration for hydrogen atom: ₁H 1s¹.
Valence electron in hydrogen atom is in 1s atomic orbital.
The atomic number (Z) determines total number of protons and uniquely identifies a chemical element, also the atomic number is equal to the number of electrons.
4) Answer is: wood.
Different forms of the same element that have different properties because of different atom arrangements are called allotropes.
Carbon has many allotropes, but two most important are graphite and diamomd.
Graphite has sp2 and diamond has sp3 hybridization of carbon atoms, because of that graphite conduct electricity and diamond not.
In diamond carbon atoms are arranged in the face centered cubic crystal structure called a diamond lattice.
Diamond has very strong covalent bonds between carbon atoms and because of that it has the highest hardness and thermal conductivity of any bulk substance.
5) Answers are:
Coke is a residue that remains after volatile products distill off from the heating of coal.
Pollution is a problem related to burning soft coal.
Coal undergoes decomposition when heated to high temperature in the absence of air.
Coke is a fuel made by heating coal in the absence of air. It is the solid carbonaceous material derived from destructive distillation.
Anthracite is the highest rank of coal. It is a hard, brittle and black lustrous coal.
Most often greenhouse gases are carbon dioxide and methane. They come from burning multiple substances: coal, petroleum, natural gas.
Carbon dioxide (CO₂) and energy (heat) is produced by combustion of fossil fuels, that energy is used for producing electricity (the heat energy of combustion is converted into mechanical energy).
For example, coal power plants use coal to heat water into steam, that steam.
6) Answer is: 1s22s22p2.
Carbon is a chemical element with symbol C and atomic number 6, which means it has 6 protons and six electrons. Four valence electrons are in 2s and 2p orbitals.
Electron configuration of carbon atom: ₆C 1s² 2s² 2p².
The atomic number (Z) determines total number of protons and uniquely identifies a chemical element, also the atomic number is equal to the number of electrons.
7) Answer is: covalent.
For example chemical compound CCl₄ (carbon tetrachloride).
There are four single covalent bonds between one carbon atom and four chlorine atoms.
Carbon has sp3 hybridization (hybridize one s-orbital and three p-orbitals) and four chlorine atoms are positioned symmetrically as corners in a tetrahedral configuration. Because of symmetrical geometry, carbon tetrachloride is non-polar molecule.
8) Answers are:
Carbon dioxide is not an organic compound.
Carbon chains can form branches and cross-links.
Carbon compounds can be rings.
Carbon monoxide (CO) and carbon dioxide (CO₂) are inorganic compounds.
Carbon form rings, for example benzene.
All of the carbon-carbon bonds in benzene are identical.
All six carbon atoms in bezene are sp2 hybridized.
All of the carbon-carbon bonds have exactly the same lengths, that length is somewhere between single and double bonds.
Benzene is very stable because delocalized electrons above and below the plane of the ring.
