Chess on Tablet

Detailed answers to the "why?" questions that come up in the opening explanations.

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Why is Black's f7 square weak?

In the starting position, the f7 pawn is defended only by the king. Most of Black's other pawns are defended by two or more pieces.

• Only the king defends it: if White attacks f7 with two pieces, Black is one defender short.
• It is right next to the king: losing f7 opens the king to checks. It can cost more than a pawn and even lead to mate.
• It is easy to reach: a bishop on c4, a queen on h5 or f3, and a knight on g5 can all hit f7 early in the game.

For example, 1. e4 e5 2. Bc4 Nc6 3. Qh5 Nf6?? 4. Qxf7# attacks f7 with the bishop and queen and mates in four moves (Scholar's Mate).

After castling, the king goes to g8 and the rook on f8 also defends f7, so the weakness goes away. For the same reason, White's f2 square is weak too.

Why can White usually win back the c4 pawn?

After 1. d4 d5 2. c4, if Black takes with 2...dxc4, it is hard for Black to keep the extra pawn.

• The bishop wins it back: after e3 (or e4), the bishop on f1 can reach c4. White recaptures with Bxc4 and the bishop lands on a good square.
• Holding on breaks Black's pawns: if Black defends c4 with ...b5, White attacks b5 with a4. The longer Black tries to keep the pawn, the weaker Black's queenside pawns become.
• Sometimes the queen wins it back: in some lines, Qa4+ gives check and then takes on c4.

While winning the pawn back, White can also play e4 and hold the center with two pawns, because Black's d5 pawn has left the center for c4.

That is why 2. c4 is called a gambit (a move that offers a pawn), but it is not a real pawn sacrifice. This line is called the Queen's Gambit.