What is the covalent (single bond) value of sodium?
CREATE TABLE "atomic_radii" (
  "number" real,
  "symbol" text,
  "name" text,
  "empirical" text,
  "calculated" text,
  "van_der_waals" text,
  "covalent_single_bond" text,
  "covalent_triple_bond" text
);
SELECT "covalent_single_bond" FROM "atomic_radii" WHERE "name"='sodium';