Marcus Johansson, Marcus Pettersson and Joel Eriksson scored for the Swedes, whose eight-game winning run in the tournament came to an end.
The Czechs jumped into a 5-2 lead in the second period after the teams had been tied at 2-2.
Kase gave the Czechs a 3-2 advantage from close range 6:05 in the period, and that was the first time the Swedes had trailed in the tournament.
Necas doubled the advantage with a one-timed slap shot from the slot after Kampf won a faceoff 16 seconds later. Kubalik then made it 5-2 with a one-timer from the right circle that went between the pads of goaltender Filip Gustavsson.
The goalie was pulled after letting in five goals from 17 shots and replaced by Samuel Ersson.
Joel Eriksson reduced the Czech lead to 5-3 on a power play with his seventh goal of the tournament.
Sweden piled on the pressure in the third period but Sedlak, who plays for Pardubice in the Czech league, stretched the lead to 7-3 with two breakaway goals, both going between the pads of Ersson.
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AP sports: https://apnews.com/sports
Karel Janicek, The Associated Press